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epidemics期刊最新论文

发布时间:2024-07-04 05:26:01

epidemics期刊最新论文

波德里亚-崛起的空白走向边缘 作为一个水印的意外,而且也考虑到其他不可预见的事件的想法是设想在即将进入90年代之间的几个朋友成立一个机构将无形的,匿名的,秘密的,隐身处,同样被称为: ANATHEMATIC无限 TRANSFATAL明示 病毒纳入 国际流行病 为了追捕虚幻的事件公众,它本身仍然不现实的。从这个意义上讲,完全履行了它的作用,因为它设法逃脱所有的雷达探测,成为一个独特的公式,是从来没有的虚拟。 这意味着什么是不再有想法,有什么不符合事实-这是“乌托邦”的六十年代和七十年代-即不再有任何行动者参与的事件,没有被占领的知识分子与意义。相反,有一个微不足道的动乱事件,缺乏真正的行动者,并授权口译:行动[近诉讼]同时消失的拍卖[近权威] 。所有这一切依然是“时事” ,是一种电影“行动” ,一个“拍卖” ,即价格标签的活动在一个谎的信息。这次活动是采取行动不仅在行动,但在投机,并最终在一个连锁反应,联系真实性极端的方式,没有任何解释可以加入它。

你好呀,我是动作缓慢的程序猿。 元旦的时候我看到一个特别离谱的谣言啊,具体是什么内容我就不说了,我怕脏了大家的眼睛。 但是,我看到一个群里传的那叫一个绘声绘色,大家讨论的风生水起的,仿佛大家就在现场似的。 这事吧本来我呵呵一笑也就过了。但是隔了一会我突然大腿一拍:这是个素材啊。我可以和大家聊一个共识算法呀。 说到共识算法,大家首先想到的应该都是 Raft、Paxos、Zab 算法这类理解起来比较困难的强一致性算法。 但是还有一个弱一致性的共识算法比较好理解,Gossip 协议。 Gossip,先看这个单词,圈起来,要考的啊,这是一个六级词汇,也是考研单词,意思是“流言蜚语”。 接下来就带你简单的看看这个“流言蜚语”到底是怎么回事。 Gossip 协议 Gossip 协议最早提出的时间得追溯到 1987 年发布的一篇论文:《Epidemic Algorithms for Replicated Database Maintenance》 我第一次看到这个论文的名字的时候,我都懵逼了:这也没有 Gossip 的关键词呢。 主要是 Epidemic Algorithms 这两个单词,我又恰好认识。 Algorithms,算法,没啥说的。 Epidemic 是啥? 紧扣当下时事:所以 Epidemic Algorithms 翻译过来就是流行病算法。 因此 Gossip 的学名应该是又叫做“流行病算法”,只是大家更喜欢叫它 Gossip 而已。毕竟,虽不喜欢听点儿“小道消息”呢? 说论文之前,先简单定个基调。 你觉得一致性协议最基础、最核心、最重要的一个动作是什么? 是不是数据更新? 为了保证各个节点的数据的一致性,必然就涉及到数据的更新操作。 所以,在论文的开篇介绍部分描述了三种方法来进行数据的更新: Direct mail(直接邮件) Anti-entropy(反熵) Rumor mongering(传谣) Direct mail(直接邮寄) 废话先不说了,直接上个图:上面这图啥意思呢? 就是一共八个小圆点,假设每个都代表一个服务器,它们之间都是平等的关系,不存在中心节点、主从什么的关系。 其中最上面的红色节点表示该节点有数据变更了,于是把变更的数据直接通知给剩下的节点。 如果其他的节点上发生了数据变更也是同样的道理。 可以简单的理解为一个循环遍历,每发生一次数据变更,为了保持数据的一致性,就得进行一次循环遍历。 这个方案的优点很明显:简单、粗暴、直接。 但是缺点和优点一样明显,我们看看论文里面怎么说: 主要看 but 的部分: 首先不完全可靠,因为这个要求每个站点都必须知道所有站点的存在。但是实际情况是有的站点并不总是知道所有其他站点。 然后,信息(mail)有时会丢失,一旦丢失,就连最终一致性也保证不了,整个凉凉。 其实 Direct mail(直接邮寄)并不是论文里面主要讨论的方案,把它写在第一个起一个抛砖引玉的作用。 主要聊聊 Anti-entropy(反熵)和 Rumor-Mongering(传谣)这两个方案。 先定个整体的基调: Anti-entropy(反熵),是传播节点上的所有的数据 Rumor-Mongering(传谣),是传播节点上的新到达的、或者变更的数据 说白了,一个是全量,一个是增量。 Anti-entropy(反熵) 部分同学可能对“反熵”这个词感到莫名其妙哈,其实主要是不了解啥是“熵”。 其实说白了,“熵”的通俗理解就是“混乱程度”。 比如你的房间,如果你不去整理那么各自物品的摆放就会越来越混乱,也就是越来越“熵”。而你整理房间的这个操作就是“反熵”。 这个东西你可以简单的先这样理解,我一时半会也给你说不清楚,这东西要聊下去的话得上升到宇宙和哲学的高度。 我主要怕你听不懂。 在论文里面是这样的描述 Anti-entropy 模式的: 每个服务器有规律地随机选择另一个服务器,这二者通过交换各自的内容来抹平它们之间的所有差异,这种方案是非常可靠的。 (but 开始了)但需要检查各自服务器的全量内容,言外之意就是数据量略大,因此不能使用太频繁。 实验表明,反熵虽然可靠,但传播更新的速度比直接邮件慢得多。 如果不同步,那么两者之间的数据差异越来越大,也就是越来越熵。 同步的目的是缩小差异,达到最终一致性,这就是反熵。 定义就是这么个定义。 Rumor mongering(传谣) 比起反熵,传谣从字面上就很好理解了。 比如我是一个大学生,并不能完全认识整个学校的人。但是学校里面的同学之间都有千丝万缕的联系。 假设有一天,我刚好碰见校花一个人走在路上,我就上去和她讨论了一下计算机领域里面的共识算法等相关问题,关于这些问题我们进行了深入的讨论并且交换了彼此的理解和看法。 咱这边就是说,整个过程是越讨论越激烈,不知道怎么走着走着就走到了情人坡。 应该每个大学都有一个叫做情人坡的地方吧。 然后被别的妹子看见了。她就给她闺蜜说:你知道歪歪吗?对,就是大一新生,那个大帅比。我那会看到他和校花在情人坡那边溜达。 然后一传十、十传百。这个消息全校师生都知道了。 “歪歪和校花在情人坡那边溜达”这个消息就通过 gossip 的传谣模式,达到了最终一致性。 “传谣”和“反熵”的差别在于只传递新信息或者发生了变更的信息,而不需要传递全量的信息。 比如上面的这个例子中,只需要同步“歪歪和校花在情人坡那边溜达”这个最新的消息就行。 而不需要同步“歪歪是谁,校花是谁,情人坡在哪”等等这些之前大家早就达成一致性的信息。在提到“传谣”和“反熵”的时候,论文中还有这么个定义: simple epidemics:单纯性传染病 在这种模式下,包含两种状态:infective(传染性) 和 susceptible(易感染)。 处于 infective 状态的节点代表其有数据更新,需要把数据分享(传染)给其他的节点。 处于 susceptible 状态的节点代表它还没接受到其他节点的数据更新(没有被感染)。 所以,后面我提到“感染”的时候,你应该要知道我是从这里看到的,不是胡编的。 关于“传谣”和“反熵”,再借用周志明老师《凤凰架构》里面的正经一点的描述,是这样的: 达到一致性耗费的时间与网络传播中消息冗余量这两个缺点存在一定对立,如果要改善其中一个,就会恶化另外一个。 由此,Gossip 设计了两种可能的消息传播模式:反熵(Anti-Entropy)和传谣(Rumor-Mongering),这两个名字都挺文艺的。 熵(Entropy)是生活中少见但科学中很常用的概念,它代表着事物的混乱程度。 反熵的意思就是反混乱,以提升网络各个节点之间的相似度为目标,所以在反熵模式下,会同步节点的全部数据,以消除各节点之间的差异,目标是整个网络各节点完全的一致。 但是,在节点本身就会发生变动的前提下,这个目标将使得整个网络中消息的数量非常庞大,给网络带来巨大的传输开销。 而传谣模式是以传播消息为目标,仅仅发送新到达节点的数据,即只对外发送变更信息,这样消息数据量将显著缩减,网络开销也相对较小。 一个网站 摊牌了,其实我是看到了这个网站,才决定写这篇文章的。 因为这个网站里面直接有非常仿真的动画模拟 gossip 协议的同步过程,一个动图胜过千言万语。 地址先放在这里,大家可以自己访问玩儿一下: 先给你看一眼它的工作过程: 甭管看没看懂吧,这玩意至少看起来很厉害的样子。 接下来就给你介绍一下它是怎么玩的: 首先我们看这里的 Nodes 和 Fanout。 Nodes 其实很好理解,就是节点数,这里的 40 就代表下面的小圆圈的个数,比如我今年 18 岁,那么我把它改成 18 它就是这样的:主要是这个 Fanout 是个啥玩意呢? 在这个网页的头部的轮播图里面,第一张图是这样的: 答案就藏在这个 Learn more 里面。 这段话里面就解释了,什么是 Fanout。同时也简单的介绍了 gossip 协议的基本工作原理。 它说 gossip 协议在概念上非常简单,编码也非常简单。它们背后的基本想法是这样的: 一个节点想与网络中的其他节点分享一些信息。然后,它定期从节点集合中随机选择一个节点并交换信息,收到信息的节点也做同样的事情。 该信息定期发送到 N 个目标,N 被称为扇出(Fanout)。 所以,前面的 Fanout=4,含义就是某个节点,每次会把自己想要分享的信息同步给集群中的另外 4 个节点。 在模拟器中体现出来应该是这样的:上面这个图你可以看到有很多线,但是它们的起点都是一个红色的节点。 这个红色的节点就是你用鼠标随意点击小圆圈中的一个或者多个都可以,鼠标一点击就会变成红色,就是完犊子了,红码了,表示“被感染”了。 上面的线条是怎么搞出来的呢? 有了一个红色的小圆圈之后,点击上面的“Show Paths”就会出现路径了: 但是不是说好 Fanout=4 吗,为什么怎么多的路径? 因为,虽然这个节点知道这么多其他节点,但是它只会选择其中的 4 个进行感染。 上面这个图还是有点复杂,所以我把参数都调小一点,这样看起来就清爽多了:集群中有一个节点的信息更新了,这个节点知道其他 5 个节点的存在,但是它只会把信息推送给其中的两个,点击 Send Message 按钮之后就会像是这样: 你可以发现上面这个图里面已经有三个红色的节点了,有两条路径变粗了,含义是从这个路径传播过来的。 整个集群最终会全部完成“感染”,达成最终一致性: 同时,gossip 协议它也具备容错性: 按照页面上的提示,我们是可以通过 “Delete” 按钮删除一部分路径的,比如下面这样:删除两个路径,代表这几个节点之间是不可达的,但是最终这个集群还是会全部被感染。 再来个动图演示一下,可以看到路径删除后,这个节点再也不会给对应的节点通讯,但是整个集群还是达到了收敛: 你自己也可以打开网站去玩一下,还有一个小技巧是这样的: 点击 Play 按钮,是可以随时暂停的,这样就更容易观察到整个传播的过程。 最后,关于这个图里面,还有一个关键的东西没有说,就是里面的这个公式: 在 Learn More 里面也有提到这个公式,其实它就是 gossip 协议的复杂度,O(logN) :比如,每次都设置为 Fanout=4,那么节点数和预估传播轮次之间的关系是这样的: 40 个节点, 轮 80 个节点, 轮 160 个节点, 轮 320 个节点, 轮 640 个节点, 轮 ... 可以看到,随着节点数的翻倍增加,传播轮次并没有明显的增加。 这就是前面 Learn More 截图里面提到的这个词:Scalable 这是个四级词汇啊,会考的,记住了,是“可伸缩”的意思。 采用 gossip 协议的集群,Scalable is very 的 nice。 其他注意点 在这个网站上,最重要的就是它的动图模拟功能了,但是也不要忽略了它里面的其他部分的描述。 比如这一段话,我就觉得非常的重要。 这一段话里面提到了两个问题,我一个个的说。 首先它说在网站模拟的过程中,所有节点发送消息似乎都是同步的,就像有一个全局循环一样。 在模拟中这样做,是因为这样看起来更加的直观。 但是,在一个真正的 gossip 协议中,每个节点都有自己的周期,它们之间根本没有也不需要同步。 上面是说什么意思呢? 我再说的直白一点,每个节点往外同步消息的时候,是按照自己的周期来处理的,比如每 10 秒一次。根本就不关心其他节点什么时候触发同步消息的操作,只需要管好自己就行了。 第二问题我认为就很重要了: How do the nodes know about each other? 节点之间怎么知道其他节点的存在的? 其中一个方式就是当节点加入集群时,必须知道该集群中的一个节点的信息。通过前面的动图我们知道,如果一个节点被另外一个节点知道,那么它最终也一定会被感染。 那问题就来了:新节点加入时又是如何知道集群中一个节点信息的呢? 很简单,我知道的一个方案就是人工指定。 Redis 集群采用的就是 gossip 协议来交换信息。当有新节点要加入到集群的时候,需要用到一个 meet 命令。 这玩意就是人工指定。 还有一个可以注意一下的是这个: 这里提到了另外一个模拟的网站: 它可以通过控制这几个参数,来测算集群达成一致性的时间。上面这个图表示的就是在信息交换频率(GOSSIP INTERVAL)为 ,Fanout 节点数为 3,总节点数为 30,丢包率和节点失败率为 0 的这个情况。 在这个情况下,对应的到达最终一致性的时间图长这样: 基本上在一秒的时间就搞定了。 你也可以自己去修改一下参数,看看对应的时间图的变化。 比如,我只修改节点数,把它从 30 修改为 3000,时间图变成了这样: 在 左右完成了收敛。 节点扩大 100 倍,但是时间增加不到 1s,确实是很优秀。 这玩意好是好,但是给你看个刺激的,来感受一下这恐怖的传播规模:从动图中可以看出,前面一两次传播还好,至少眼睛还能看出个大概,但是到了后几轮,大多数节点都被感染了,但是还在继续对外传播消息。 这消息数量,简直是看的让人头皮发麻。 六度分隔理论 最后再说一个有意思的东西,叫做“六度分隔理论”: 1967年,哈佛大学的心理学教授Stanley Milgram想要描绘一个连结人与社区的人际连系网。做过一次连锁信实验,结果发现了“六度分隔”现象。简单地说:“你和任何一个陌生人之间所间隔的人不会超过六个,也就是说,最多通过六个人你就能够认识任何一个陌生人。 六度分割理论,也叫小世界理论。这其实和 Gossip 协议也有千丝万缕的联系。 我在小破站上看到一个相关的视频,我觉得解释的还是挺清楚的,你如果有兴趣的话可以去看看: 在视频里面,有这样的一个画面: 好家伙,这不是我们前面的网站上面的翻版嘛,看起来可太亲切了。 这个理论刚刚提出来的时候还是“最多通过六个人你就能够认识任何一个陌生人”。 但是随着这几年社交网络的急速发展,地球都被拉小到了一个“村”的概念了。 所以这个数字在逐渐的减少: 而且如果把这个范围拉小一点,比如局限在程序员这个小范围内,那就更小了。 有时候拉个业务对接群,进去一看好家伙还有前同事,你说这个圈子能有多大。 本文已收录到个人博客,欢迎大家来玩。

混沌学 Chaos theoryIn mathematics, chaos theory describes the behavior of certain dynamical systems – that is, systems whose state evolves with time – that may exhibit dynamics that are highly sensitive to initial conditions (popularly referred to as the butterfly effect). As a result of this sensitivity, which manifests itself as an exponential growth of perturbations in the initial conditions, the behavior of chaotic systems appears to be random. This happens even though these systems are deterministic, meaning that their future dynamics are fully defined by their initial conditions, with no random elements involved. This behavior is known as deterministic chaos, or simply behaviour is also observed in natural systems, such as the weather. This may be explained by a chaos-theoretical analysis of a mathematical model of such a system, embodying the laws of physics that are relevant for the natural behavior has been observed in the laboratory in a variety of systems including electrical circuits, lasers, oscillating chemical reactions, fluid dynamics, and mechanical and magneto-mechanical devices. Observations of chaotic behaviour in nature include the dynamics of satellites in the solar system, the time evolution of the magnetic field of celestial bodies, population growth in ecology, the dynamics of the action potentials in neurons, and molecular vibrations. Everyday examples of chaotic systems include weather and climate.[1] There is some controversy over the existence of chaotic dynamics in the plate tectonics and in economics.[2][3][4]Systems that exhibit mathematical chaos are deterministic and thus orderly in some sense; this technical use of the word chaos is at odds with common parlance, which suggests complete disorder. A related field of physics called quantum chaos theory studies systems that follow the laws of quantum mechanics. Recently, another field, called relativistic chaos,[5] has emerged to describe systems that follow the laws of general well as being orderly in the sense of being deterministic, chaotic systems usually have well defined statistics.[citation needed] For example, the Lorenz system pictured is chaotic, but has a clearly defined structure. Bounded chaos is a useful term for describing models of first discoverer of chaos was Henri Poincaré. In 1890, while studying the three-body problem, he found that there can be orbits which are nonperiodic, and yet not forever increasing nor approaching a fixed point.[6] In 1898 Jacques Hadamard published an influential study of the chaotic motion of a free particle gliding frictionlessly on a surface of constant negative curvature.[7] In the system studied, "Hadamard's billiards," Hadamard was able to show that all trajectories are unstable in that all particle trajectories diverge exponentially from one another, with a positive Lyapunov of the earlier theory was developed almost entirely by mathematicians, under the name of ergodic theory. Later studies, also on the topic of nonlinear differential equations, were carried out by . Birkhoff,[8] A. N. Kolmogorov,[9][10][11] . Cartwright and . Littlewood,[12] and Stephen Smale.[13] Except for Smale, these studies were all directly inspired by physics: the three-body problem in the case of Birkhoff, turbulence and astronomical problems in the case of Kolmogorov, and radio engineering in the case of Cartwright and Littlewood. Although chaotic planetary motion had not been observed, experimentalists had encountered turbulence in fluid motion and nonperiodic oscillation in radio circuits without the benefit of a theory to explain what they were initial insights in the first half of the twentieth century, chaos theory became formalized as such only after mid-century, when it first became evident for some scientists that linear theory, the prevailing system theory at that time, simply could not explain the observed behaviour of certain experiments like that of the logistic map. What had been beforehand excluded as measure imprecision and simple "noise" was considered by chaos theories as a full component of the studied main catalyst for the development of chaos theory was the electronic computer. Much of the mathematics of chaos theory involves the repeated iteration of simple mathematical formulas, which would be impractical to do by hand. Electronic computers made these repeated calculations practical, while figures and images made it possible to visualize these systems. One of the earliest electronic digital computers, ENIAC, was used to run simple weather forecasting early pioneer of the theory was Edward Lorenz whose interest in chaos came about accidentally through his work on weather prediction in 1961.[14] Lorenz was using a simple digital computer, a Royal McBee LGP-30, to run his weather simulation. He wanted to see a sequence of data again and to save time he started the simulation in the middle of its course. He was able to do this by entering a printout of the data corresponding to conditions in the middle of his simulation which he had calculated last his surprise the weather that the machine began to predict was completely different from the weather calculated before. Lorenz tracked this down to the computer printout. The computer worked with 6-digit precision, but the printout rounded variables off to a 3-digit number, so a value like was printed as . This difference is tiny and the consensus at the time would have been that it should have had practically no effect. However Lorenz had discovered that small changes in initial conditions produced large changes in the long-term outcome.[15] Lorenz's discovery, which gave its name to Lorenz attractors, proved that meteorology could not reasonably predict weather beyond a weekly period (at most).The year before, Benoit Mandelbrot found recurring patterns at every scale in data on cotton prices.[16] Beforehand, he had studied information theory and concluded noise was patterned like a Cantor set: on any scale the proportion of noise-containing periods to error-free periods was a constant – thus errors were inevitable and must be planned for by incorporating redundancy.[17] Mandelbrot described both the "Noah effect" (in which sudden discontinuous changes can occur, ., in a stock's prices after bad news, thus challenging normal distribution theory in statistics, aka Bell Curve) and the "Joseph effect" (in which persistence of a value can occur for a while, yet suddenly change afterwards).[18][19] In 1967, he published "How long is the coast of Britain? Statistical self-similarity and fractional dimension," showing that a coastline's length varies with the scale of the measuring instrument, resembles itself at all scales, and is infinite in length for an infinitesimally small measuring device.[20] Arguing that a ball of twine appears to be a point when viewed from far away (0-dimensional), a ball when viewed from fairly near (3-dimensional), or a curved strand (1-dimensional), he argued that the dimensions of an object are relative to the observer and may be fractional. An object whose irregularity is constant over different scales ("self-similarity") is a fractal (for example, the Koch curve or "snowflake", which is infinitely long yet encloses a finite space and has fractal dimension equal to circa , the Menger sponge and the Sierpiński gasket). In 1975 Mandelbrot published The Fractal Geometry of Nature, which became a classic of chaos theory. Biological systems such as the branching of the circulatory and bronchial systems proved to fit a fractal was observed by a number of experimenters before it was recognized; ., in 1927 by van der Pol[21] and in 1958 by . Ives.[22][23] However, Yoshisuke Ueda seems to have been the first experimenter to have identified a chaotic phenomenon as such by using an analog computer on November 27, 1961. The chaos exhibited by an analog computer is a real phenomenon, in contrast with those that digital computers calculate, which has a different kind of limit on precision. Ueda's supervising professor, Hayashi, did not believe in chaos, and thus he prohibited Ueda from publishing his findings until 1970.[24]In December 1977 the New York Academy of Sciences organized the first symposium on Chaos, attended by David Ruelle, Robert May, James Yorke (coiner of the term "chaos" as used in mathematics), Robert Shaw (a physicist, part of the Eudaemons group with J. Doyne Farmer and Norman Packard who tried to find a mathematical method to beat roulette, and then created with them the Dynamical Systems Collective in Santa Cruz), and the meteorologist Edward following year, Mitchell Feigenbaum published the noted article "Quantitative Universality for a Class of Nonlinear Transformations", where he described logistic maps.[25] Feigenbaum had applied fractal geometry to the study of natural forms such as coastlines. Feigenbaum notably discovered the universality in chaos, permitting an application of chaos theory to many different 1979, Albert J. Libchaber, during a symposium organized in Aspen by Pierre Hohenberg, presented his experimental observation of the bifurcation cascade that leads to chaos and turbulence in convective Rayleigh–Benard systems. He was awarded the Wolf Prize in Physics in 1986 along with Mitchell J. Feigenbaum "for his brilliant experimental demonstration of the transition to turbulence and chaos in dynamical systems".[26]The New York Academy of Sciences then co-organized, in 1986, with the National Institute of Mental Health and the Office of Naval Research the first important conference on Chaos in biology and medicine. Bernardo Huberman thereby presented a mathematical model of the eye tracking disorder among schizophrenics.[27] Chaos theory thereafter renewed physiology in the 1980s, for example in the study of pathological cardiac 1987, Per Bak, Chao Tang and Kurt Wiesenfeld published a paper in Physical Review Letters[28] describing for the first time self-organized criticality (SOC), considered to be one of the mechanisms by which complexity arises in nature. Alongside largely lab-based approaches such as the Bak–Tang–Wiesenfeld sandpile, many other investigations have centred around large-scale natural or social systems that are known (or suspected) to display scale-invariant behaviour. Although these approaches were not always welcomed (at least initially) by specialists in the subjects examined, SOC has nevertheless become established as a strong candidate for explaining a number of natural phenomena, including: earthquakes (which, long before SOC was discovered, were known as a source of scale-invariant behaviour such as the Gutenberg–Richter law describing the statistical distribution of earthquake sizes, and the Omori law[29] describing the frequency of aftershocks); solar flares; fluctuations in economic systems such as financial markets (references to SOC are common in econophysics); landscape formation; forest fires; landslides; epidemics; and biological evolution (where SOC has been invoked, for example, as the dynamical mechanism behind the theory of "punctuated equilibria" put forward by Niles Eldredge and Stephen Jay Gould). Worryingly, given the implications of a scale-free distribution of event sizes, some researchers have suggested that another phenomenon that should be considered an example of SOC is the occurrence of wars. These "applied" investigations of SOC have included both attempts at modelling (either developing new models or adapting existing ones to the specifics of a given natural system), and extensive data analysis to determine the existence and/or characteristics of natural scaling same year, James Gleick published Chaos: Making a New Science, which became a best-seller and introduced general principles of chaos theory as well as its history to the broad public. At first the domains of work of a few, isolated individuals, chaos theory progressively emerged as a transdisciplinary and institutional discipline, mainly under the name of nonlinear systems analysis. Alluding to Thomas Kuhn's concept of a paradigm shift exposed in The Structure of Scientific Revolutions (1962), many "chaologists" (as some self-nominated themselves) claimed that this new theory was an example of such as shift, a thesis upheld by J. availability of cheaper, more powerful computers broadens the applicability of chaos theory. Currently, chaos theory continues to be a very active area of research, involving many different disciplines (mathematics, topology, physics, population biology, biology, meteorology, astrophysics, information theory, etc.).[edit] Chaotic dynamicsFor a dynamical system to be classified as chaotic, it must have the following properties:[30]it must be sensitive to initial conditions, it must be topologically mixing, and its periodic orbits must be dense. Sensitivity to initial conditions means that each point in such a system is arbitrarily closely approximated by other points with significantly different future trajectories. Thus, an arbitrarily small perturbation of the current trajectory may lead to significantly different future to initial conditions is popularly known as the "butterfly effect", so called because of the title of a paper given by Edward Lorenz in 1972 to the American Association for the Advancement of Science in Washington, . entitled Predictability: Does the Flap of a Butterfly’s Wings in Brazil set off a Tornado in Texas? The flapping wing represents a small change in the initial condition of the system, which causes a chain of events leading to large-scale phenomena. Had the butterfly not flapped its wings, the trajectory of the system might have been vastly to initial conditions is often confused with chaos in popular accounts. It can also be a subtle property, since it depends on a choice of metric, or the notion of distance in the phase space of the system. For example, consider the simple dynamical system produced by repeatedly doubling an initial value (defined by iterating the mapping on the real line that maps x to 2x). This system has sensitive dependence on initial conditions everywhere, since any pair of nearby points will eventually become widely separated. However, it has extremely simple behaviour, as all points except 0 tend to infinity. If instead we use the bounded metric on the line obtained by adding the point at infinity and viewing the result as a circle, the system no longer is sensitive to initial conditions. For this reason, in defining chaos, attention is normally restricted to systems with bounded metrics, or closed, bounded invariant subsets of unbounded for bounded systems, sensitivity to initial conditions is not identical with chaos. For example, consider the two-dimensional torus described by a pair of angles (x,y), each ranging between zero and 2π. Define a mapping that takes any point (x,y) to (2x, y + a), where a is any number such that a/2π is irrational. Because of the doubling in the first coordinate, the mapping exhibits sensitive dependence on initial conditions. However, because of the irrational rotation in the second coordinate, there are no periodic orbits, and hence the mapping is not chaotic according to the definition mixing means that the system will evolve over time so that any given region or open set of its phase space will eventually overlap with any other given region. Here, "mixing" is really meant to correspond to the standard intuition: the mixing of colored dyes or fluids is an example of a chaotic systems are never chaotic; for a dynamical system to display chaotic behaviour it has to be nonlinear. Also, by the Poincaré–Bendixson theorem, a continuous dynamical system on the plane cannot be chaotic; among continuous systems only those whose phase space is non-planar (having dimension at least three, or with a non-Euclidean geometry) can exhibit chaotic behaviour. However, a discrete dynamical system (such as the logistic map) can exhibit chaotic behaviour in a one-dimensional or two-dimensional phase space.[edit] AttractorsSome dynamical systems are chaotic everywhere (see . Anosov diffeomorphisms) but in many cases chaotic behaviour is found only in a subset of phase space. The cases of most interest arise when the chaotic behaviour takes place on an attractor, since then a large set of initial conditions will lead to orbits that converge to this chaotic easy way to visualize a chaotic attractor is to start with a point in the basin of attraction of the attractor, and then simply plot its subsequent orbit. Because of the topological transitivity condition, this is likely to produce a picture of the entire final instance, in a system describing a pendulum, the phase space might be two-dimensional, consisting of information about position and velocity. One might plot the position of a pendulum against its velocity. A pendulum at rest will be plotted as a point, and one in periodic motion will be plotted as a simple closed curve. When such a plot forms a closed curve, the curve is called an orbit. Our pendulum has an infinite number of such orbits, forming a pencil of nested ellipses about the origin.[edit] Strange attractorsWhile most of the motion types mentioned above give rise to very simple attractors, such as points and circle-like curves called limit cycles, chaotic motion gives rise to what are known as strange attractors, attractors that can have great detail and complexity. For instance, a simple three-dimensional model of the Lorenz weather system gives rise to the famous Lorenz attractor. The Lorenz attractor is perhaps one of the best-known chaotic system diagrams, probably because not only was it one of the first, but it is one of the most complex and as such gives rise to a very interesting pattern which looks like the wings of a butterfly. Another such attractor is the Rössler map, which experiences period-two doubling route to chaos, like the logistic attractors occur in both continuous dynamical systems (such as the Lorenz system) and in some discrete systems (such as the Hénon map). Other discrete dynamical systems have a repelling structure called a Julia set which forms at the boundary between basins of attraction of fixed points - Julia sets can be thought of as strange repellers. Both strange attractors and Julia sets typically have a fractal Poincaré-Bendixson theorem shows that a strange attractor can only arise in a continuous dynamical system if it has three or more dimensions. However, no such restriction applies to discrete systems, which can exhibit strange attractors in two or even one dimensional initial conditions of three or more bodies interacting through gravitational attraction (see the n-body problem) can be arranged to produce chaotic complexity of a chaotic systemSimple systems can also produce chaos without relying on differential equations. An example is the logistic map, which is a difference equation (recurrence relation) that describes population growth over time. Another example is the Ricker model of population the evolution of simple discrete systems, such as cellular automata, can heavily depend on initial conditions. Stephen Wolfram has investigated a cellular automaton with this property, termed by him rule minimal model for conservative (reversible) chaotic behavior is provided by Arnold's cat map.

为了追捕虚幻的事件公众,它本身仍然不现实的。从这个意义上讲,完全履行了它的作用,因为它设法逃脱所有的雷达探测,成为一个独特的公式,是从来没有的虚拟。 这意味着什么是不再有想法,有什么不符合事实-这是“乌托邦”的六十年代和七十年代-即不再有任何行动者参与的事件,没有被占领的知识分子与意义。相反,有一个微不足道的动乱事件,缺乏真正的行动者,并授权口译:行动[近诉讼]同时消失的拍卖[近权威] 。所有这一切依然是“时事” ,是一种电影“行动” ,一个“拍卖” ,即价格标签的活动在一个谎的信息。这次活动是采取行动不仅在行动,但在投机,并最终在一个连锁反应,联系真实性极端的方式,没有任何解释可以加入它。 希望大家支持我!

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财讯杂志不会停刊。根据查询相关信息,近期财讯杂志任然活跃,不存在停刊。《财讯》杂志是经国家新闻出版总署批准,面向国内外公开发行的全国综合性教育理论学术期刊。由广东财讯杂志社主办,面向全国各级各类大、中专经济院校工作者。银行、经贸委、财政及行政管理人员

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中国会计评论由北京大学、清华大学、北京国家会计学院联合发起、16所综合大学加盟创办的《中国会计评论》(China Accounting Review),由北京大学出版创刊号。会计研究是CSSCI来源期刊中唯一的会计类学术期刊,是学术界公认的会计学权威期刊。 《会计研究》内容涵盖财务会计、财务管理、管理会计、公司治理、审计等多个领域,读者群体主要是国内外具有较好理论基础的会计研究人员 。

会计与经济研究《会计与经济研究》(双月刊)1983年创刊,(原名《上海立信会计学院学报》)是由上海市教委主管、上海立信会计学院主办的以会计为主、贸易金融经济为辅的财经类学术期刊。财务与会计主管主办:国家财政部  中国财政杂志社快捷分类:经济会计 经济与管理科学

时代商家期刊和财讯期刊都是省级经济类刊物,财讯期刊涉及面比时代商家要广泛的多。

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龙源收录的期刊不正规。论文考试答辩取消、条件放宽文件政策,搜:高级职称论文价格+要我发.先起腰(发)我就发腰、全国论文办+要我发.先起腰(发)我就发腰、高级职称论文取消+要我发.先起腰(发)我就发腰,把热线的第7个字(发)换成汉字八(下同),其他换成数字(下同),再搜,翻到158页后(下同),有文件政策。也可搜:高级职称论文热线+要我发.先起腰.发我就发腰、高级经济师论文热线+要我发.先起腰.发我就发腰、高级会计师论文热线要我发.先起腰.发我就发腰、(任何)论文热线要我发.先起腰.发我就发腰、全国高级职称热线要我发.先起腰.发我就发腰、职称论文期刊杂志投稿热线要我发.先起腰.发我就发腰、全国企业管理热线要我发.先起腰.发我就发腰、全国企业培训热线要我发.先起腰.发我就发腰、全国企业咨询热线要我发.先起腰.发我就发腰、全国总裁培训热线要我发.先起腰.发我就发腰、全国高管教练热线要我发.先起腰.发我就发腰、全国论文企管办热线要我发.先起腰.发我就发腰(换成电话再搜)、全国论文和企业管理培训咨询办公室热线要我发.先起腰.发我就发腰、即搜:全国(论文、职称、高级职称、期刊、高级职称论文、高级经济师论文、高级会计师论文、任何职称论文、企业管理、企业培训、企业咨询、总裁培训、高管教练)热线+要我发.先起腰【发】我就发腰。 也可搜:《全国论文热线要我发.先起腰.发我就发腰(换成同音数字再搜)总结的职称评审经验教训》《全国论文热线要我发.先起腰.发我就发腰(换成同音数字再搜)20年创建的企业管理培训咨询名牌被网上假冒经历》《高级职称论文郑密路全国办被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《高级经济师论文郑密路网被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《高级经济师论文郑密路全国办被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《高级经济师考试论文网158被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《高级经济师考试网158被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《河南职称论文大学被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《郑州职称论文大学被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《郑州高级职称论文大学被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《郑州论文大学被网上假冒已更名,只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)》《防假冒只能搜:高级职称论文热线要我发.先起腰.发我就发腰(换成电话再搜)、企业管理培训热线要我发.山齐腰.发我就发腰、企业咨询热线要我发.先起腰.发我就发腰、总裁CEO培训热线要我发.山齐腰.发我就发腰、高管教练热线要我发.山齐腰.发我就发腰》《标【广告】的各种郑州论文企业管理咨询培训商业推广多是假冒不在郑州》《全国论文导师企业管理咨询培训师郑州文力教授被假冒到只能公开手机号的程度》《找全国论文导师企业管理咨询培训师郑州文力教授只能搜手机号热线要我发.先起腰.发我就发腰》。 领导说想找啥,就搜:(啥)热线要我发.山齐腰.发我就发腰。搜后翻到百度360搜狗58-68页,都能找到答案。限职称、企业培训咨询任何问题。例:搜:论文热线要我发.山齐腰.发我就发腰,可找到论文期刊、查重等所有信息;搜:高级经济师热线要我发.山齐腰.发我就发腰,可找到报考评审条件、考试科目用书等所有信息;搜:高级经济师论文热线要我发.山齐腰.发我就发腰,可找到范文、选题、发表期刊字数要求等所有信息;搜:高级经济师论文范文热线要我发.山齐腰.发我就发腰,可找到大量范文;搜:企业管理培训咨询热线要我发.山齐腰.发我就发腰,可找到课程、老师等所有信息;搜:企业培训机构排名前十热线要我发.山齐腰.发我就发腰,可找到机构、课程、老师等所有信息;搜:高管教练热线要我发.山齐腰.发我就发腰,可找到课程、老师等所有信息;搜:华人十大杰出总裁教练热线要我发.山齐腰.发我就发腰,可找到课程、老师等所有信息......为什么领导说只能搜“关键词+热线要我发.先起腰.发我就发腰”?因为文力教授太出名了,引起全国几百人争相网上假冒。网上唯一无法假冒的是热线。所以领导说只能搜“关键词+热线”。文力教授主要从事高级职称考试教用书编著、论文辅导、企业管理培训咨询工作,样样出名,无论做什么、取什么名称,只要是汉字,都会引来大量网上假冒,已经把郑州文力教授假冒到只能公开“热线要我发.山齐腰.发我就发腰”的程度。防假冒只能搜:高级职称论文取消热线要我发.先起腰.发我就发腰、企业管理培训热线要我发.山齐腰.发我就发腰、企业咨询热线要我发.先起腰.发我就发腰、总裁CEO培训热线要我发.山齐腰.发我就发腰、高管教练热线要我发.山齐腰.发我就发腰。文力教授在全国的影响大到什么程度?全国闻名的郑州郑密路20号论文街、企管街、职称街(郑州文力教授地址)就是因文力教授而生的。文力教授一人带动三个产业、引发全国几百人争相假冒。搜:高级经济师论文、高级会计师论文、各种论文、企业管理培训咨询类、高级职称辅导类关键词,会发现标【广告】的郑州论文商业推广最多。其实都不在郑州,都是假冒郑州文力教授。识别假冒也简单:搜【广告】手机电话,不在郑州,必是假冒。点击【广告】二字,会出现百度提示:本搜索结果为商业推广信息,请注意可能的风险。文力教授热线“热线要我发.山齐腰.发我就发腰、热线要我发.先起腰.发我就发腰、要发腰.山齐腰.玲玲山齐山、要发腰.先起腰.玲玲山齐山”早已出现在百度相关搜索中。全国没有第二个人有这么大的知名度和影响力。文力教授旗下高手荟萃、精英云集:博硕导师、经管博士、美国访问学者、ICF国际认证高管教练、哈佛清北浙复交博士......。中国富豪论坛对联就是郑州文力教授写的:浪淘沙,物竞天择铸精英;大智勇,古往今来成英雄。透出的古文功底和凌然大气,非常人可比。哪些人在假冒?请转发,共同防。一、高级职称考试用书编著、论文指导方面的网上假冒(一)直接假冒:白天早8:00-晚9:00手机百度“郑州职称论文大学、河南职称论文大学、郑州论文大学”,下标【广告】的全是假冒、都不在郑州。白天搜到的假冒多,晚上少。手机百度搜到的假冒多。电脑百度搜到的少。(二)直接假冒:电脑百度“河南职称论文大学、高级经济师论文郑密路网、高级经济师考试论文网158、高级职称论文郑密路全国办、郑密路论文网”,下标【广告】的全是假冒、都不在郑州。电脑百度搜到的假冒多,手机百度搜到的少。这个浏览器搜不到,那个浏览器能搜到。以上都是郑州文力教授17年创建的名牌,全部被假冒。已经把郑州文力教授假冒到只能公开手机的程度。连郑州文力教授所在地郑州郑密路也成为名牌、被全国几百人假冒。全国只有郑州一个城市有郑密路。网上假冒郑密路的竟然有北京上市企业。搜索总经理姓名,发现新闻界赞美一片(国内顶尖大学硕士、中国职业教育领军人物等)。再搜索他公司名称(某某网校、北京某科技发展有限公司),网上骂声一片,投诉几百条。(三)间接变相假冒:搜各种郑州论文,下标【广告】的全是假冒、都不在郑州。 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龙源收录的期刊不正规。从2022年4月开始,几乎在一夜之间,之前我们一直说的那些只上龙源的盗版刊物,全都被龙源期刊网屏蔽了。比如《家园·电力与科技》《家园·电力与科技》(学术)《科学导报》(学术)《科学与生活》《科学与生活》(学术版)《民族文汇》《安家·校外教育》《安家(建筑与工程)》《家庭药师》《文学天地》《科学家》《三悦文摘》《中国学术期刊—教育与社科辑 》《中国典型病例大全》等等。不管是电脑端还是手机端,都一样没法检索到这些“刊物”。而且在电脑端,也无法再使用“全部检索”功能。同时,龙源期刊网在其官网发表声明,声明截图如下。

声明重点在于这几点。1.龙源从未参与期刊收取和投稿行为(,不管你刊物真假,龙源确实没有参与发行行为。2.我要求是必须正版授权,而且我肯定要坚持正版授权。。种种迹象表明,龙源要对旗下的刊物进行整顿了,确实问题太多了,这个情况大家反馈的太多了,毕竟一连串盗版刊物都在在杵着,你不整顿,那很容易被大家视为是在助纣为虐,最终沦为期刊网、中国期刊网、中刊网那种人人喊打的野鸡数据库。

最新数学期刊

四大顶级期刊: 《数学年刊》 Annals of Mathematics 《数学新进展》Inventions Mathematics 《数学学报》 Acta Mathematicas 《美国数学会杂志》Journal Of The American Mathematical Society 2021年的目标是做一只潜心读书的好金牛。

我国数学类的核心刊物主要有:

1、数学学报。

2、数学研究与评论。

3、数学年刊。

4、应用数学学报。

5、计算数学。

6、数学进展。

7、数学杂志。

8、系统科学与数学。

9、应用数学。

10、应用概率统计。

11、高等学校计算数学学报。

12、高校应用数学学报。

13、系统工程理论与实践。

14、数学的实践与认识。

15、数学物理学报。

16、数理统计与应用概率。

17、运筹学学报。

18、工程数学学报。

19、系统工程。

数学期刊数学专业刊物。

它是传播、交流数学科学学术思想,并及时反映数学科学研究成果的有力工具。它的出现是数学科学事业发展的需要,反过来又有力地促进了数学事业的发展。

1.数学学报 2.数学年刊.A辑 3.应用数学学报 4.计算数学 5.数学进展 6.数学研究与评论 7.系统科学与数学 8.数学物理学报 9.应用概率统计 10.工程数学学报 11.应用数学 12.数学杂志 13.高校应用数学学报.A辑 14.模糊系统与数学 15.高等学校计算数学学报 16.数学季刊 17.工科数学(改名为:大学数学) 18.数学的实践与认识 19.纯粹数学与应用数学 20.运筹学学报 21.数学教育学报 都是忙着发论文的人。

理论数学、应用数学进展都是rccse的核心刊

insight期刊最新论文

1、论文题目:要求准确、简练、醒目、新颖。2、目录:目录是论文中主要段落的简表。(短篇论文不必列目录)3、提要:是文章主要内容的摘录,要求短、精、完整。字数少可几十字,多不超过三百字为宜。4、关键词或主题词:关键词是从论文的题名、提要和正文中选取出来的,是对表述论文的中心内容有实质意义的词汇。关键词是用作机系统标引论文内容特征的词语,便于信息系统汇集,以供读者检索。 每篇论文一般选取3-8个词汇作为关键词,另起一行,排在“提要”的左下方。主题词是经过规范化的词,在确定主题词时,要对论文进行主题,依照标引和组配规则转换成主题词表中的规范词语。5、论文正文:(1)引言:引言又称前言、序言和导言,用在论文的开头。 引言一般要概括地写出作者意图,说明选题的目的和意义, 并指出论文写作的范围。引言要短小精悍、紧扣主题。〈2)论文正文:正文是论文的主体,正文应包括论点、论据、 论证过程和结论。主体部分包括以下内容:a.提出-论点;b.分析问题-论据和论证;c.解决问题-论证与步骤;d.结论。6、一篇论文的参考文献是将论文在和写作中可参考或引证的主要文献资料,列于论文的末尾。参考文献应另起一页,标注方式按《GB7714-87文后参考文献著录规则》进行。中文:标题--作者--出版物信息(版地、版者、版期):作者--标题--出版物信息所列参考文献的要求是:(1)所列参考文献应是正式出版物,以便读者考证。(2)所列举的参考文献要标明序号、著作或文章的标题、作者、出版物信息。

近五年作为通讯作者,共发表了研究论文200余篇,其中被SCI收录180余篇,主要发表在国际著名的Adv. Funct. Mater.、Chem: .、Chem. Commun.、J. Mater. Chem.、 J. Phys. Chem. B、J. Phys. Chem. C、J. Comput. Chem.、Inorg. Chem.、Appl. Catal. B、Nanotechnology、J. Phys.: Condensed Matter等学术期刊上,影响因子在以上的论文有50余篇,其中影响因子在以上8篇。成果被SCI收录期刊正面引用1400余次。出版专著两部,美国科学出版社邀请为纳米科学技术大百科全书撰写了完整的一章。申请发明专利14项。已发表和已录用的主要论文清单如下(以下均为SCI期刊收录论文,*代表通讯联系人)·Pan Qing-Jiang,Guo Yuan-Ru,Li Li,Fu Hong-Gang*,and Zhang Hong-Xing “Structures,Spectroscopic Properties and Redox Potentials of Quaterpyridyl Ru(Ⅱ) Photosensitizer and its Derivatives for Solar Energy Cell: A Density Functional Study” Physical Chemistry Chemical Physics 2011,DOI:.·Gao Xiao-Qin,Pan Qing-Jiang,Li Li,Guo Yuan-Ru,Zhang Hong-Xing,Fu Hong-Gang* “Structures and Spectroscopic Properties of Ruthenium Phenanthroline Solar-Cell Sensitizers: A Computational Study” Chemical Physics Letters,2011,506,146-151.·Zhou W,Sun FF,Pan K,Tian GH,Fu HG*. Well-ordered large-pore mesoporous anatase TiO2 with remarkably high thermal stability and improved crystallinity: Preparation,characterization and photocatalytic performance. Advanced Functional Materials,2011,21,1922-1930..·Jiang Baojiang,Tian CG,Fu Honggang*,et al. In-Situ Growth of TiO2 in Interlayers of Expanded Graphite for the Fabrication of TiO2-Graphene with Enhanced Photocatalytic Activity. Chemistry-A European Journal,2011,Accepted,.· Li Sun,Chungui Tian,Lei Wang,Jinlong Zou,Guang Mu,Honggang Fu*,Magnetically Separable Porous Graphitic Carbon with Large Surface Area as Excellent Adsorbents for Metal Ions and Dye. Journal of Materials Chemistry,2011,2011,21,7232-7239.· Zhao H,Yang J,Wang L,Tian CG,Jiang BJ,Fu HG*. Fabrication of palladium nanoparticles/graphene nanosheets hybrid via sacrifice of copper template and its application in catalytic oxidation of formic acid. Chemical Communications,2011,47,2014-2016.· Yang J,Tian CG,Wang L,Fu HG*. An effective strategy to small-sized and high-dispersed palladium nano particles supported on graphene with excellent performance for formic acid oxidation. Journal of Materials Chemistry,2011,21,3384-3390.· Tian GH,Chen YJ,Zhou W,Ren ZY,Tian CG,Fu HG*. Facile solvothermal synthesis of hierarchical flower-like Bi2MoO6 hollow spheres as high performance visible-light driven photocatalysts. Journal of Materials Chemistry,2011,21,887 – 892.· Hu ZF,Shen PK*,Fu HG*,et al. Oxygen Reduction Electrocatalysis Enhanced by Nanosized Cubic Vanadium Carbide. Electrochemistry Communications,2011,Accepted,ELECOM 3881.· Tian Guohui,Chen Yajie,Zhou Wei,Pan Kai,Huang Xu-ri and Fu Honggang *,3D hierarchical flower-like TiO2 nanostructure: morphology control and its photocatalytic property. 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编译 冯维维

Science , 23 July 2021, Vol 373, Issue 6553

《科学》 2021年7月23日,第373卷,6553期

天体物理学 Astrophysics

Peta–electron volt gamma-ray emission from the Crab Nebula

来自蟹状星云的高能光子

作者:The LHAASO Collaboration

链接:

摘要

蟹状星云含有一颗脉冲星,它能激发周围的气体释放出高能辐射。脉冲星的年轻及其附近的位置使得该星云成为天空中最亮的伽马射线源。

作者报道了这种源在1012到1015电子伏的能量下的观察结果,扩展了这种原型物体的光谱。

他们将这些数据与较低能量下的观测数据结合起来,以模拟辐射过程的物理过程。多波长数据可以用同步辐射和逆康普顿散射的结合来解释。

Abstract

The Crab Nebula contains a pulsar that excites the surrounding gas to emit high-energy radiation. The combination of the pulsar's youth and nearby location makes the nebula the brightest gamma-ray source in the sky. Cao et al. report observations of this source at energies of tera– to peta–electron volts, extending the spectrum of this prototypical object. They combine these data with observations at lower energies to model the physics of the emission process. The multiwave-length data can be explained by a combination of synchrotron radiation and inverse Compton scattering.

Upper mantle structure of Mars from InSight seismic data

“洞察号”地震数据揭示火星上地幔结构

作者:Amir Khan, Savas Ceylan, William B. Banerdt, etc.

链接:

摘要

两年来,“洞察号”着陆器一直在记录火星上的地震数据,这些数据对了解火星的结构和热化学状态至关重要。作者利用8个低频火星地震的直接(P和S)和地表反射(PP、PPP、SS和SSS)体波相的观测,将内部结构限制在800公里的深度。

他们发现了一种与低速带相容的结构,该低速带与热岩石圈比地球上厚得多,这可能与远震距离上的弱s波阴影带有关。通过结合地震约束和地球动力学模型,作者预测,相对于原始地幔,地壳的产热元素更丰富,是原始地幔的13 - 20倍。

这种富集比伽玛射线地表测绘所建议的要大,并且具有中等到高的地表热流。

Abstract

For 2 years, the InSight lander has been recording seismic data on Mars that are vital to constrain the structure and thermochemical state of the planet. We used observations of direct (P and S) and surface-reflected (PP, PPP, SS, and SSS) body-wave phases from eight low-frequency marsquakes to constrain the interior structure to a depth of 800 kilometers. We found a structure compatible with a low-velocity zone associated with a thermal lithosphere much thicker than on Earth that is possibly related to a weak S-wave shadow zone at teleseismic distances. By combining the seismic constraints with geodynamic models, we predict that, relative to the primitive mantle, the crust is more enriched in heat-producing elements by a factor of 13 to 20. This enrichment is greater than suggested by gamma-ray surface mapping and has a moderate-to-elevated surface heat flow.

Thickness and structure of the martian crust from InSight seismic data

“洞察号”地震数据揭示火星地壳厚度和结构

作者:Brigitte Knapmeyer-Endrun, Mark P. Panning, Felix Bissig, W. Bruce Banerdt, etc.

链接:

摘要

行星的地壳见证了行星的形成和演化 历史 ,但对于火星来说,还没有对地壳厚度的绝对测量。作者利用火星地震记录和周围波场确定了洞察号登陆点下方地壳的结构。

通过分析在地下界面反射和转换的地震相,他们发现观测结果与模型相符,至少有两个界面,也可能有三个界面。如果第2个界面为地壳边界,厚度为20 5公里;如果第3个界面为地壳边界,厚度为39 8公里。

全球重力和地形图允许对整个星球进行这种点测量,显示火星地壳的平均厚度在24到72公里之间。独立的体积组成和地球动力学约束表明,较厚的模型与观测到的浅层地壳产热元素的丰度一致,而较薄的模型则需要在深度上更大的浓度。

Abstract

A planet’s crust bears witness to the history of planetary formation and evolution, but for Mars, no absolute measurement of crustal thickness has been available. Here, we determine the structure of the crust beneath the InSight landing site on Mars using both marsquake recordings and the ambient wavefield. By analyzing seismic phases that are reflected and converted at subsurface interfaces, we find that the observations are consistent with models with at least two and possibly three interfaces. If the second interface is the boundary of the crust, the thickness is 20 5 kilometers, whereas if the third interface is the boundary, the thickness is 39 8 kilometers. Global maps of gravity and topography allow extrapolation of this point measurement to the whole planet, showing that the average thickness of the martian crust lies between 24 and 72 kilometers. Independent bulk composition and geodynamic constraints show that the thicker model is consistent with the abundances of crustal heat-producing elements observed for the shallow surface, whereas the thinner model requires greater concentration at depth.

Seismic detection of the martian core

火核的地震探测

作者:Simon C. Stähler, Amir Khan, W. Bruce Banerdt, Suzanne E. Smrekar

链接:

摘要

一颗行星的地质 历史 线索包含在它的内部结构中,尤其是它的核心。作者利用“洞察号”地震数据探测到来自火星核-地幔边界的地震波反射,并将其与大地测量数据进行反演,将液态金属核的半径限制在1830 40公里。

巨大的地核表明火星地幔在矿物学上类似于地球上的上地幔和过渡带,但与地球不同的是没有以桥曼石为主的下地幔。我们推断出核的平均密度为每立方厘米至克,这就需要大量的轻元素溶解在铁镍核中。

从洞察号的位置上看到的地震核心阴影覆盖了火星表面的一半,包括大多数潜在的活跃区域。这可能限制了可探测到的火星地震的数量。

Abstract

Clues to a planet’s geologic history are contained in its interior structure, particularly its core. We detected reflections of seismic waves from the core-mantle boundary of Mars using InSight seismic data and inverted these together with geodetic data to constrain the radius of the liquid metal core to 1830 40 kilometers. The large core implies a martian mantle mineralogically similar to the terrestrial upper mantle and transition zone but differing from Earth by not having a bridgmanite-dominated lower mantle. We inferred a mean core density of to grams per cubic centimeter, which requires a substantial complement of light elements dissolved in the iron-nickel core. The seismic core shadow as seen from InSight’s location covers half the surface of Mars, including the majority of potentially active regions—., Tharsis—possibly limiting the number of detectable marsquakes.

粒子物理学 Particle Physics

Coherent manipulation of an Andreev spin qubit

安德烈夫自旋量子位的相干操纵

作者:M. Hays, V. Fatemi, D. Bouman, J. Cerrillo, S. Diamond, K. Serniak, T. Connolly, P. Krogstrup, J. Nygård, A. Levy Yeyati, A. Geresdi, M. H. Devoret

链接:

摘要

到目前为止,发展量子信息处理系统最有希望的固态方法是基于超导电路的循环超电流和操纵半导体量子点中电子的自旋特性。

作者结合了这两种方法的可取之处,超导电路的可扩展性和量子点的紧凑空间,来设计和制造超导自旋量子比特。

这个所谓的安德烈夫自旋量子位提供了开发一个新的量子信息处理平台的机会。

Abstract

To date, the most promising solid-state approaches for developing quantum information-processing systems have been based on the circulating supercurrents of superconducting circuits and manipulating the spin properties of electrons in semiconductor quantum dots. Hays et al. combined the desirable aspects of both approaches, the scalability of the superconducting circuits and the compact footprint of the quantum dots, to design and fabricate a superconducting spin qubit (see the Perspective by Wendin and Shumeiko). This so-called Andreev spin qubit provides the opportunity to develop a new quantum information processing platform.

Inhibited nonradiative decay at all exciton densities in monolayer semiconductors

在单层半导体的所有激子密度下抑制无辐射衰减

作者:Hyungjin Kim, Shiekh Zia Uddin, Naoki Higashitarumizu, Eran Rabani, Ali Javey

链接:

摘要

由于激子发生非辐射湮灭,单层过渡金属二卤族的光致发光量子产额在高发射强度下普遍下降。作者指出,这一过程在这些材料中通过它们的联合态密度的van Hove奇点共振放大。

然而,小的机械应变(约)的应用改变了van Hove奇点,抑制了非辐射过程。在剥离的硫化钼、硫化钨和硒化钨单分子层以及化学气相沉积的厘米级硫化钨单分子层中,都可以看到高激子密度下的近统一光致发光量子产额。

Abstract

The photoluminescence quantum yield in monolayer transition metal dichalcogenides generally drops at high emission intensities because the excitons undergo nonradiative annihilation. Kim et al. show that this process is resonantly amplified in these materials by van Hove singularities in their joint density of states. However, application of small mechanical strains ( ) shifted the van Hove singularities and suppressed the nonradiative processes. Near-unity photoluminescence quantum yield at high exciton densities was seen in exfoliated monolayers of molybdenum sulfide, tungsten sulfide, and tungsten selenide, as well as centimeter-scale tungsten sulfide monolayers grown by chemical vapor deposition.

Atomically resolved single-molecule triplet quenching

原子分辨单分子三态猝灭

作者:Jinbo Peng, Sophia Sokolov, Daniel Hernangómez-Pérez, Ferdinand Evers, Leo Gross4, John M. Lupton, Jascha Repp

链接:

摘要

分子的非平衡三重态在光催化、有机光伏和光动力治疗等方面发挥着重要作用。作者通过引入原子力显微镜中的电子泵浦探针方法,报告了直接测量单个并五苯分子在绝缘表面上的三重态寿命的原子分辨率。

如果氧分子在近距离内共吸附,可以观察到三重态寿命的强烈猝灭。通过单分子操作技术,与氧分子的不同排列被创造出来,并以原子精度表征,允许分子排列与淬灭三重态的寿命直接相关。

这种单分子长寿命三联体的电寻址,结合原子尺度的操作,为控制和研究局部自旋-自旋相互作用提供了以前未 探索 的途径。

Abstract

The nonequilibrium triplet state of molecules plays an important role in photocatalysis, organic photovoltaics, and photodynamic therapy. We report the direct measurement of the triplet lifetime of an inpidual pentacene molecule on an insulating surface with atomic resolution by introducing an electronic pump-probe method in atomic force microscopy. Strong quenching of the triplet lifetime is observed if oxygen molecules are coadsorbed in close proximity. By means of single-molecule manipulation techniques, different arrangements with oxygen molecules were created and characterized with atomic precision, allowing for the direct correlation of molecular arrangements with the lifetime of the quenched triplet. Such electrical addressing of long-lived triplets of single molecules, combined with atomic-scale manipulation, offers previously unexplored routes to control and study local spin-spin interactions.

生态学 Ecology

Innovation and geographic spread of a complex foraging culture in an urban parrot

城市鹦鹉复杂觅食文化的创新和地理传播

作者:Barbara C. Klump, John M. Martin, Sonja Wild, Jana K. Hörsch, Richard E. Major, Lucy M. Aplin

链接:

摘要

文化创新的出现、传播和建立可以促进对人类变化的适应性反应。作者描述了一个发展适应城市环境的文化的假定案例:野生硫冠凤头鹦鹉打开家庭垃圾箱。

社区科学报告的空间网络分析揭示了通过 社会 学习,鹦鹉打开从澳大利亚郊区的3个垃圾箱到悉尼市区44个垃圾箱的地理分布。对160个直接观察结果的分析揭示了个体风格和特定地点的差异。

作者描述了从创新的传播到地理变异的出现的完整路径,证明了鹦鹉的觅食文化,并表明了鹦鹉文化复杂性的存在。垃圾箱的打开与人类提供的机会直接相关,突出了文化促进对人类变化的行为反应的潜力。

Abstract

The emergence, spread, and establishment of innovations within cultures can promote adaptive responses to anthropogenic change. We describe a putative case of the development of a cultural adaptation to urban environments: opening of household waste bins by wild sulphur-crested cockatoos. A spatial network analysis of community science reports revealed the geographic spread of bin opening from three suburbs to 44 in Sydney, Australia, by means of social learning. Analysis of 160 direct observations revealed inpidual styles and site-specific differences. We describe a full pathway from the spread of innovation to emergence of geographic variation, evidencing foraging cultures in parrots and indicating the existence of cultural complexity in parrots. Bin opening is directly linked to human-provided opportunities, highlighting the potential for culture to facilitate behavioral responses to anthropogenic change.

生命科学 Life Science

Enterically derived high-density lipoprotein restrains liver injury through the portal vein

肠内高密度脂蛋白通过门静脉抑制肝损伤

作者:Yong-Hyun Han, Emily J. Onufer, Li-Hao Huang, Robert W. Sprung, W. Sean Davidson, Rafael S. Czepielewski, Mary Wohltmann, Mary G. Sorci-Thomas, Brad W. Warner, Gwendalyn J. Randolph

链接:

摘要

高密度脂蛋白(HDL)对胆固醇代谢很重要,可能具有抗炎和抗菌特性。虽然HDL主要由肝脏产生,但肠道也是一个来源。

作者在小鼠实验中发现,肠道高密度脂蛋白不会进入体循环。而是以HDL3的形式,通过肝门静脉直接输送到肝脏。在那里,它将细菌的脂多糖从肠道中隔离出来,这些脂多糖会引发炎症和肝脏损伤。

在各种肝损伤模型中,肠道高密度脂蛋白的丢失加重了病理。相比之下,提高肠道高密度脂蛋白的药物可改善疾病结果。HDL - 3在门静脉血液中富集,提示肠内HDL可能是治疗肝病的靶点。

Abstract

High-density lipoprotein (HDL) is important for cholesterol metabolism and may have anti-inflammatory and antimicrobial properties. Although HDL is mainly produced by the liver, the intestine is also a source. Han et al. show in mice that intestinal HDL is not routed to the systemic circulation. Rather, in the form of HDL3, it is directly transported to the liver through the hepatic portal vein. There, it sequesters bacterial lipopolysaccharide from the gut that can trigger inflammation and liver damage. In various models of liver injury, loss of enteric HDL exacerbated pathology. By contrast, drugs elevating intestinal HDL improved disease outcomes. HDL3 is enriched in human portal venous blood, suggesting that enteric HDL may be targetable for the treatment of liver disease.

Retinal waves prime visual motion detection by simulating future optic flow

视网膜波通过模拟未来光流实现视觉运动检测

作者:Xinxin Ge, Kathy Zhang, Alexandra Gribizis, Ali S. Hamodi, Aude Martinez Sabino, Michael C. Crair

链接:

摘要

当一只老鼠在森林的地面上向前奔跑时,它所经过的风景是向后流动的。作者的研究表明,发育中的小鼠视网膜提前实践了眼睛在小鼠移动时必须处理的东西。

视网膜活动的自发波与几天后在环境中实际运动时产生的波形相同。这种自发的模式活动改善了大脑上丘细胞的反应能力,上丘接收来自视网膜的神经信号以处理方向性信息。

Abstract

As a mouse runs forward across the forest floor, the scenery that it passes flows backwards. Ge et al. show that the developing mouse retina practices in advance for what the eyes must later process as the mouse moves. Spontaneous waves of retinal activity flow in the same pattern as would be produced days later by actual movement through the environment. This patterned, spontaneous activity refines the responsiveness of cells in the brain's superior colliculus, which receives neural signals from the retina to process directional information.

第一步. 调研、入门1. 确定一个感兴趣的大领域,比如分布式系统或者机器学习,或者深度神经网络。读这个领域经典算法和技术,也可以是几本比较好的书,读完然后再实践实践,动手加深理解。这个过程做完就算是初步入门了。2. 找该领域的顶级会议,比如系统领域的有OSDI、SOSP,机器学习的领域有ICML、CVPR,深度学习的有NIPS、ICLR等等,可以搜CCF会议推荐列表看各领域的顶会列表。然后看近几年这些顶会的论文,因为这代表了最新的研究热点,咱不是说一味的追热点啊,毕竟对于初学者没有足够的领域专业背景,追热点是最快的方法。因为热点往往是该领域最亟待解决的问题,往往是发展最快的小方向,也最容易产生新成果。如果是老问题,人家都研究十几年了,给你留下的待解决的问题就很少或者不是很重要。当然如果是有几十年经验的研究者就不必追热点,他们知道该领域哪些是fundamental的问题,哪些是最值得研究的问题。3. 读了这些前沿论文后,确定一个小方向,比如分布式系统是个大方向,小方向可能是机器学习分布式训练;大方向是深度学习,小方向可能就是graph embedding;大方向是机器学习,小方向可能是半监督学习等等。确定小方向的过程是个知识不断积累的过程,非常重要,这需要你对大方向有很多了解,对小方向有更深入更全面的理解,需要读好至少100篇以上论文,需要你知道该小方向的研究进展历史,这需要你知道该小方向别人都在哪方面做工作,做该小方向的顶级研究组都有哪些,他们正在干什么。第二步. 发现问题这步超级难,如果发现了个好问题,那就是成功的一半。这个问题最好是重要的、本质的、没有直观解决方法的。4. 确定小方向后,你需要阅读大量的这个小方向的论文和了解开源项目,再不断聚焦,再确定一个要改进和优化的小小方向,这个可能就是论文的主题。小小方向可能是机器学习分布式系统中的parameter server通信模型,可能是dynamic graph embedding等。然后就要更聚焦地读这方面的相关论文,这时候论文就比较少了,几篇到几十篇到几百篇都有可能,这些论文要精读,花几个月时间研究一篇论文也不为过。5. 挑几个重要的论文工作实现,也可以找开源的运行跑一跑试一试,idea往往从实际运行中来,光靠读是不行的。这个跑一跑可能需要你尝试不同的运行环境,不同的workload数据集,不同的应用场景等。比如,parameter server(PS)模型在本地集群上跑是不是和paper声明的一样、在异构的动态性极强的集群环境下效果怎么样、除了paper提到的算法处理其他算法的时候效果怎么样、除了paper提到的数据集换另外一类数据集怎么样;graph embedding方法处理密集图和稀疏图都怎么样,处理动态变化的图怎么样,等等吧。你要发现X方法仅在a环境下好用,在b环境不好用。这个就是发现问题的过程。当然,没经验的研究者可能很难想到多种环境、多种workload、多种应用场景,这就需要积累。另外一个发现问题的方法是从实际生产中来,这个当然是最好的,但是往往是大企业环境下才有这个条件。6. 确定你发现的问题还没有被解决。这又需要广泛的阅读和调研,但是问题已经很聚焦了,搜索也会很容易,用你特定问题的关键字在google 搜索(这里强烈建议用google,其他搜索引擎基本搜不到),找到解决相关问题的论文。看看这些论文是不是已经解决了该问题,如果解决了,你有两种方案:第一,该问题已经解决的非常好了,放弃解决该问题。第二,该问题的解决方案还有问题,我还有更好的办法。我建议后者,最起码尽量尝试尝试。5和6步是个迭代的过程…第三步. 分析问题7. 分析问题产生的本质原因。这个往往和第5步发现问题同时进行。这一步靠的是功底和积累,靠的是对问题的理解程度。理解的越深刻,分析的越透测,你之后产生的解决思路就越有可能正确和有效。比如分布式机器学习的PS模型在异构环境下、和在处理数据不均匀的情况下就不好,本质原因是其同步的集中式通信模型,造成PS集中服务器往往需要等待。传统graph embedding方法采用批处理模式,需要graph的全局信息做embedding,当然无法应付动态性非常强的局部更新情况。8. 基于分析,就是对该问题的深刻理解,产生改进的idea。这个可能很难,可能靠运气,但我觉得更多的是靠对问题的理解程度,理解的越深刻,本质原因抓的越准,就越可能产生创新idea。读过一本介绍google企业文化的书,google产品的成功,既不是靠技术能力,也不是靠用户需求,而是靠技术洞见(insight),这就是对问题本质的深刻理解。比如,PS模型在某环境下问题的本质原因是集中式的同步模型,那么我们就可以提出尝试异步通信的模型的idea。分析能力跟个人的批判性思维、独立思考能力都有关,而这正是中国人欠缺的,可以通过读有深刻见地的书籍文章、经常提问来锻炼。第四步. 解决问题9. 实现你的idea,做大量实验验证。这需要动手能力,需要编程能力,需要坐得住。10. 验证你的解决方案,根据实验分析不断优化你的方法。做了大量试验后,得到了若干结果,可能是不好的结果,但是不要一下子否定自己的解决方案,这不能说明你的idea不好用。一个好的方法往往经过千锤百炼,同样,你的idea通常不会一下子就成功。需要你根据实验结果分析不好的原因,然后基于你的理解改进方法,这是一个反复不断迭代的过程。比如,你发现异步PS模型效果还不如原来的呢。那么关键的是,你要问自己为什么?为什么理应提升的却没有提升?你要看实验运行的日志,看看是哪里慢了,差在哪里,最后你经过不断的实验、分析、思考,你发现了,你提出的异步PS模型虽然没有了等待开销,但是计算的有效性却降低了,结果整体性能反而下降了。那么你下一次迭代就要想怎么把这个计算有效性提上来。我又有了个方法,可以评估每次计算的有效性,然后把计算资源都投到有效性高的计算上。OK,idea不错,那么怎么评估有效性呢?不能开销太大,否则又得不偿失了,你可能想到了一种近似地评估方法。重新实现后,发现效果还不错。OK,恭喜你!你可以准备发论文了!整个研究过程,导师将起到关键的作用。导师可能会给你个问题,这是难能可贵的,基本帮你做了一半的事了,否则你可能需要花上一年时间找问题。然后整个研究过程,都是在导师的引导下进行,需要定期向导师汇报,与导师讨论idea和请导师分析实验结果。最好自己也要经常找同门讨论,而不是闭门造车。第五步. 撰写论文11. 设计你的论文,草拟论文的骨架。每一章都写啥,每一段都写啥,实验都做啥。论文的逻辑往往比语言重要的多,逻辑合理的论文更易读懂,即使咱华人有天生的英语语言缺陷,但是好的逻辑就可以弥补这个不足。写论文就和讲故事一样,怎么能把一个事说明白,不那么简单,甚至说很难,需要不断锻炼。写完给老师看,老师同意后进行下一步12. 写作论文。这个就是根据骨架填肉的过程,但是这一步也不简单,特别对于英语不好的同学,写出来的东西简直是不忍直视、不堪入目、毁人三观。最近上海某高校老师辱骂学生这事就是因为这个,我可以说,我每次看到学生论文也都是这个心情,给学生通宵改论文在家里一边改一边骂,但是当面对学生还是要以鼓励为主,要耐心,要耐心,要耐心,尽力压制自己的怒火,以平和的心态帮助学生提高,期望他下次能给个更好的版本。但是往往事与愿违,看淡点吧,仅求写作态度好点就行了,毕竟这不是一朝一夕能提高的,需要你不断积累。有几个写作的方法吧。第一,不要自己想当然,对于不确定的句型,用“”扩上上google搜,看看你这句型有多少人用过,如果没有几个人用,那就别用,换个写法。第二,读别人论文时,遇到好的句型就记下来,不断积累才能提高。第三,避免一切语法错误,我觉得这个是可以做到的,现在网上那么多工具都可以用。语法错误都避免不了那基本就是态度问题。遗憾的是,我很少遇到能避免语法错误的学生,我生气往往是因为态度问题,而不是能力问题。第四,尽量用短句用简单句子,别用长句。你写论文是为了让别人理解你的方法,不是写文艺作品,能说明白就行。13. 提炼总结,改进方法。写作的过程也是屡顺自己思路的过程,写作的过程中往往也能发现自己方法的漏洞,那么就要继续回到8,重新思考解决方案,又或者你发现需要补实验来支撑你的论点,那么就继续实现系统做实验,得到实验结果。14. 关于实验。怎么做实验是学生总问的问题,怎么做科学实验也是一个很重要的问题,有对照组、无偏的、定量的,这些都是科学实验的重要要素。如果有解决该问题的其他方法你首先要说明你的方法更好,至少在某一方面更好,这其中可能要涉及到不同的执行环境,或不同的算法数据集。然后设计实验说明你的方法好在哪里,用实验数据说明,比如异步PS和同步PS对比。然后你要进一步用实验数据说明,异步PS的有效性也提高了,如果不考虑有效性的话那么结果就不好。然后你的方法是否有些重要的超参数,试试variation导致各种结果。在实验结果展示方面,要学会用各种工具画各种图,把重要的因素用可视化方式体现出来。第六步. 投稿和看待审稿意见15. 接下来就是投稿。选一个合适的会议或期刊投稿,这个可以听老师的,老师基本有这方面的常识,根据你工作的方向和档次选择合适的去处。确定好了哪个会议期刊后,就需要按照会议期刊要求来整理论文格式,latex是必会的工具了。之后赶在deadline之前提交论文,这个最后的几天可能很痛苦,因为你的论文和方法总有改进的地方,老师的要求会让你最后几天是最忙的几天。但是需要认识到,凡事无完美,你总也改不到完美,你需要一个deadline来督促你完成一个milestone。开始进一步工作或下一个工作。16. 看待评审意见。接下来是漫长的等待,会议一般是2-3个月的时间,结果可能是接收也可能是拒掉,相比于结果,更应该看评审意见,看看这些意见是否合理,是否能解决,无论是接收还是拒绝,然后接下来就再次回到解决问题的部分,再次开始优化方法的过程。如果是接收了,那就可以准备订机票开会旅游去了。如果是拒掉那一般是有比较大的问题,那就再仔细深思下一下你的方法。继续优化,还是降低档次投个差点的会,就看你导师的了。第七步. 后续17. 宣传你的工作,扩大影响力。首先你可能是要去参加会议,做个漂亮的ppt,反复演练,争取有比较好的演讲效果。有时你导师有机会去一些地方做报告,把这个工作介绍一下,都是扩大影响力的方法。18. 开放源码。还有是尽量把自己工作的代码和数据开放,挂到网上,让别人来使用,接受别人的改进意见或者是简单的debug。咱不是专业的工程人员,也不用指望你的成果可以马上用于生产,个人觉得开放代码主要是为了让别人更好滴了解你的方法,这有助于扩大影响力,产生后续研究工作。如果有人引用你的论文、或咨询论文内容、又或是使用了你的代码和数据,这也算是你对整个科研事业有那么一丁点的贡献了,这比水论文有意义多了。整体来说,发表论文需要你有:批判思维能力,动手能力,知识面,写作能力,表达能力,英语,韧劲(抗打击能力)等等一系列能力,如果在研究生期间真能发表一篇论文,经历了以上这么多磨难和锻炼,我想你的能力也是不知不觉提高了很多,成为了该小小方向的一个小小的专家了。这对你来说,是最最重要的。这里我提到了韧劲,就是说,在解决问题过程中,你会受到不断的打击,包括来自导师的、来自自己的实验结果方面的、来自评审意见的,但是你要做的就是,站起来,继续凿,直到导师满意,知道reviewer满意,直到大家满意。别把这事想简单了,当你想象一下周围好多人都发好多sci了,而你还在为这么一篇完全未知结果的论文而这么努力的时候,我觉得大部分人可能就是缺少这个韧劲才最终以失败告终的…最后,我想再强调一下,发论文不是简单地发论文,而是通过发论文宣传你的工作,以便对某技术或人有那么一丁点影响。无论你发哪个档次的论文,只要目标正确,我觉得你都会有收获和有贡献的。相比较于为了发论文而发论文,你会觉得你是那么地高尚和高大,他们只是造废纸,而你已经对社会有贡献了…(以上内容来源于学术堂)

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