880 resultados para Flying-machines
Resumo:
Background: Flying lemurs or Colugos (order Dermoptera) represent an ancient mammalian lineage that contains only two extant species. Although molecular evidence strongly supports that the orders Dermoptera, Scandentia, Lagomorpha, Rodentia and Primates form a superordinal clade called Supraprimates (or Euarchontoglires), the phylogenetic placement of Dermoptera within Supraprimates remains ambiguous. Results: To search for cytogenetic signatures that could help to clarify the evolutionary affinities within this superordinal group, we have established a genome-wide comparative map between human and the Malayan flying lemur (Galeopterus variegatus) by reciprocal chromosome painting using both human and G. variegatus chromosome-specific probes. The 22 human autosomal paints and the X chromosome paint defined 44 homologous segments in the G. variegatus genome. A putative inversion on GVA 11 was revealed by the hybridization patterns of human chromosome probes 16 and 19. Fifteen associations of human chromosome segments (HSA) were detected in the G. variegatus genome: HSA1/3, 1/10, 2/21, 3/ 21, 4/8, 4/18, 7/15, 7/16, 7/19, 10/16, 12/22 (twice), 14/15, 16/19 (twice). Reverse painting of G. variegatus chromosome-specific paints onto human chromosomes confirmed the above results, and defined the origin of the homologous human chromosomal segments in these associations. In total, G. variegatus paints revealed 49 homologous chromosomal segments in the HSA genome. Conclusion: Comparative analysis of our map with published maps from representative species of other placental orders, including Scandentia, Primates, Lagomorpha and Rodentia, suggests a signature rearrangement (HSA2q/21 association) that links Scandentia and Dermoptera to one sister clade. Our results thus provide new evidence for the hypothesis that Scandentia and Dermoptera have a closer phylogenetic relationship to each other than either of them has to Primates.
Resumo:
松鼠科隶属于哺乳纲、啮齿目,是一类世界广布性动物,全世界共计36 属 234 种。本文通过形态分析及分子生物学方法,研究了我国松鼠科动物的分类及 系统发育关系,内容包括以下两个方面: 一、中国松鼠科动物的分类 本研究查看了中科院昆明动物研究所、中科院动物研究所、云南大学、四川 省林业科学研究院、四川大学、陕西师范大学、陕西动物研究所、西北大学、上 海自然历史博物馆、广东昆虫所馆藏该科各类群标本。同时,结合相关文献,对 各类群的外形特征进行了详细的描述和系统分类整理,我国共计10 属34 种。测 取可量性状数据共计20800 个(完整头骨共计1300 号),而且还运用多变量及单 变量分析方法进行数据分析,对部分类群的种下分类结果进行分析:1.探讨了分 布于中国境内的明纹花鼠(Tamiops mcclellandii)3 亚种的有效性。2.研究了 隐纹花鼠(Tamiops swinhoei)在中国的分化并描记了分布于四川马尔康地区的 隐纹花鼠为一新亚种(Tamiops swinhoei markamensis)。3.描记了分布于云南 省东北部昭通地区的赤腹松鼠为一新亚种:昭通亚种(Callosciurus erythraeus zhaotongensis)。4. 提出了分布于云南省无量山区的泊氏长吻松鼠为一新亚种: 无量山亚种(Dremomys pernyi wuliangshanensis)。 二、中国松鼠科动物的系统发育研究 2004-2005 年相继到滇西北高黎贡山、香格里拉,滇西南临沧地区,滇东 南马关、麻栗坡、富宁,滇东北昭通地区进行标本采集,基本收集到我国南方松 鼠科属、种样品进行分子生物学研究。 1.中国松鼠科动物各属的系统发育关系 在分析线粒体细胞色数b 基因(1040bp)序列的基础上,运用贝叶斯法 (Bayesian phylogenetic reconstruction approaches)、最简约法(Maximum parsimony method)、邻接法(Neighbor Joining method)构建中国松鼠科动物 所有属间系统发育树。结果表明:所分析的10 属分别聚集为3 群,巨松鼠属Ratufa单独成为一群,丽松鼠属Callosciurus、长吻松鼠属Dremomys、花松鼠属 Tamiops 以及线松鼠属Menetes 成为一群,松鼠属Sciurus、岩松鼠属 Sciurotamias、花鼠属Tamias、旱獭属Marmota 以及黄鼠属Spermophilus 成 为一群。在此基础上我们进一步探讨了中国松鼠科动物的分化与环境变化的关 系。 2.长吻松鼠属的系统发育关系 在分析线粒体细胞色数b 基因(378bp)序列的基础上,我们重建了长吻松 鼠属内5 个类群间的系统发育关系,结合对5 类群外部形态特征的详细比较,我 们探讨并论证了红腿长吻松鼠、橙喉长吻松鼠作为种的地位的有效性,同时论证 了该属内泊氏长吻松鼠最早分化,其次为橙腹长吻松鼠,第三是红腿长吻松鼠, 红颊长吻松鼠和橙喉长吻松鼠是最后分化的类群。
Resumo:
Zwei verschiedene optische Methoden für die Analyse von Hg2+-Ionen, die auf der Bildung von Thymin-Hg2+-Komplexen beruhen, werden vorgestellt. Bei diesen Methoden werden die Hg2+-Ionen mithilfe aggregierter Goldnanopartikel und einer auf der DNA-Chemie basierenden Maschine (siehe Schema) analysiert.
Resumo:
Control of machines that exhibit flexibility becomes important when designers attempt to push the state of the art with faster, lighter machines. Three steps are necessary for the control of a flexible planet. First, a good model of the plant must exist. Second, a good controller must be designed. Third, inputs to the controller must be constructed using knowledge of the system dynamic response. There is a great deal of literature pertaining to modeling and control but little dealing with the shaping of system inputs. Chapter 2 examines two input shaping techniques based on frequency domain analysis. The first involves the use of the first deriviate of a gaussian exponential as a driving function template. The second, acasual filtering, involves removal of energy from the driving functions at the resonant frequencies of the system. Chapter 3 presents a linear programming technique for generating vibration-reducing driving functions for systems. Chapter 4 extends the results of the previous chapter by developing a direct solution to the new class of driving functions. A detailed analysis of the new technique is presented from five different perspectives and several extensions are presented. Chapter 5 verifies the theories of the previous two chapters with hardware experiments. Because the new technique resembles common signal filtering, chapter 6 compares the new approach to eleven standard filters. The new technique will be shown to result in less residual vibrations, have better robustness to system parameter uncertainty, and require less computation than other currently used shaping techniques.
Resumo:
This paper examines scheduling problems in which the setup phase of each operation needs to be attended by a single server, common for all jobs and different from the processing machines. The objective in each situation is to minimize the makespan. For the processing system consisting of two parallel dedicated machines we prove that the problem of finding an optimal schedule is NP-hard in the strong sense even if all setup times are equal or if all processing times are equal. For the case of m parallel dedicated machines, a simple greedy algorithm is shown to create a schedule with the makespan that is at most twice the optimum value. For the two machine case, an improved heuristic guarantees a tight worst-case ratio of 3/2. We also describe several polynomially solvable cases of the later problem. The two-machine flow shop and the open shop problems with a single server are also shown to be NP-hard in the strong sense. However, we reduce the two-machine flow shop no-wait problem with a single server to the Gilmore-Gomory traveling salesman problem and solve it in polynomial time. (c) 2000 John Wiley & Sons, Inc.
Resumo:
Review of: Peter Reimann and Hans Spada (eds), Learning in Humans and Machines: Towards an Interdisciplinary Learning Science, Pergamon. (1995). ISBN: 978-0080425696
Resumo:
The scheduling problem of minimizing the makespan for m parallel dedicated machines under single resource constraints is considered. For different variants of the problem the complexity status is established. Heuristic algorithms employing the so-called group technology approach are presented and their worst-case behavior is examined. Finally, a polynomial time approximation scheme is presented for the problem with fixed number of machines.
Resumo:
The paper considers scheduling problems for parallel dedicated machines subject to resource constraints. A fairly complete computational complexity classification is obtained, a number of polynomial-time algorithms are designed. For the problem with a fixed number of machines in which a job uses at most one resource of unit size a polynomial-time approximation scheme is offered.
Resumo:
Software metrics are the key tool in software quality management. In this paper, we propose to use support vector machines for regression applied to software metrics to predict software quality. In experiments we compare this method with other regression techniques such as Multivariate Linear Regression, Conjunctive Rule and Locally Weighted Regression. Results on benchmark dataset MIS, using mean absolute error, and correlation coefficient as regression performance measures, indicate that support vector machines regression is a promising technique for software quality prediction. In addition, our investigation of PCA based metrics extraction shows that using the first few Principal Components (PC) we can still get relatively good performance.
Resumo:
We consider a problem of scheduling jobs on m parallel machines. The machines are dedicated, i.e., for each job the processing machine is known in advance. We mainly concentrate on the model in which at any time there is one unit of an additional resource. Any job may be assigned the resource and this reduces its processing time. A job that is given the resource uses it at each time of its processing. No two jobs are allowed to use the resource simultaneously. The objective is to minimize the makespan. We prove that the two-machine problem is NP-hard in the ordinary sense, describe a pseudopolynomial dynamic programming algorithm and convert it into an FPTAS. For the problem with an arbitrary number of machines we present an algorithm with a worst-case ratio close to 3/2, and close to 3, if a job can be given several units of the resource. For the problem with a fixed number of machines we give a PTAS. Virtually all algorithms rely on a certain variant of the linear knapsack problem (maximization, minimization, multiple-choice, bicriteria). © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008
Resumo:
In this paper, we provide a unified approach to solving preemptive scheduling problems with uniform parallel machines and controllable processing times. We demonstrate that a single criterion problem of minimizing total compression cost subject to the constraint that all due dates should be met can be formulated in terms of maximizing a linear function over a generalized polymatroid. This justifies applicability of the greedy approach and allows us to develop fast algorithms for solving the problem with arbitrary release and due dates as well as its special case with zero release dates and a common due date. For the bicriteria counterpart of the latter problem we develop an efficient algorithm that constructs the trade-off curve for minimizing the compression cost and the makespan.