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1.
In the problem ofparts feeding we are given a class of feasible operations for reorienting a part, and we are asked to find a fixed sequence of these operations which is guaranteed to bring the part into a known goal orientation from any possible initial orientation. Goldberg addressed this problem in [2], and showed that, for planar polygonal parts, there is always a sequence of simple operations which can be performed by a simple parallel-jaw gripper, which is guaranteed to orient the part (up to symmetry) without the use of any sensor information; he also conjectured thatO(n) steps are sufficient.In this paper we prove Goldberg's conjecture by explicitly constructing plans of at most2n – 1 steps for orienting polygonal parts in this model. We also give a lower bound on the number of steps required for such plans to show that this upper bound is tight.Finally, we extend these results to the problem ofdistinguishing among a finite set of parts using minimal sensing. Specifically, we assume that we are given a set of known polygonal parts, and a parallel-jaw gripper able to sense the distance between its jaws upon closure. We construct a simple oblivious plan of linear complexity which, when presented with a polygonal part, determines the index of this part.This research was supported in part by the NSF under Grant CCR-9207422, and by a Zumberge Fellowship. A preliminary version of this paper appeared in theProceedings of the Fourth Canadian Conference on Computational Geometry [1].  相似文献   
2.
The past decade revealed that cell identity changes, such as dedifferentiation or transdifferentiation, accompany the insulin-producing β-cell decay in most diabetes conditions. Mapping and controlling the mechanisms governing these processes is, thus, extremely valuable for managing the disease progression. Extracellular glucose is known to influence cell identity by impacting the redox balance. Here, we use global proteomics and pathway analysis to map the response of differentiating human pancreatic progenitors to chronically increased in vitro glucose levels. We show that exogenous high glucose levels impact different protein subsets in a concentration-dependent manner. In contrast, regardless of concentration, glucose elicits an antipodal effect on the proteome landscape, inducing both beneficial and detrimental changes in regard to achieving the desired islet cell fingerprint. Furthermore, we identified that only a subgroup of these effects and pathways are regulated by changes in redox balance. Our study highlights a complex effect of exogenous glucose on differentiating pancreas progenitors characterized by a distinct proteome signature.  相似文献   
3.
目的制备抗DNA单克隆抗体,用以建立特异、灵敏、简便的外源性DNA残留量测定方法。方法将小牛胸腺DNA与阳离子化的牛血清白蛋白通过Mannich反应连接成为完全抗原,免疫BALB/c小鼠得到的脾细胞与SP2/0小鼠骨髓瘤细胞融合,获得稳定分泌抗DNA单抗的杂交瘤细胞株,对抗体进行纯化、浓缩及鉴定。结果得到3株可稳定分泌抗DNA单抗的杂交瘤细胞株,单抗的ELISA间接效价分别为1∶4×103、1∶8×104和1∶1×103;亚型分别为IgM/κ、IgM/λ和IgM/κ;亲和力常数分别为3.96×108、4.04×109和1.26×108L/mol;3株细胞分泌的单抗与ctDNA、DH5αDNA、GS115DNA和H.S.DNA均有较高的结合能力,而对RNA、BSA和酪蛋白结合较弱或不能结合;3株细胞分泌的单抗识别3个不同的抗原表位;可检出4ng/ml以上的DNA。结论成功制备了3株细胞分泌的抗DNA单抗,为外源性DNA残留量免疫测定方法的深入研究奠定了基础。  相似文献   
4.
The origin of olfactory stimuli involved in the host microhabitat location inCotesia flavipes, a parasitoid of stem-borer larvae, was investigated in a Y-tube olfactometer. The response of femaleC. flavipes towards different components of the plant-host complex, consisting of a maize plant infested with two or more larvae of the stem borerChilo partellus, was tested in dualchoice tests. The concealed lifestyle of the stem-borer larvae did not limit the emission of volatiles attractive to a parasitoid. A major source of the attractive volatiles from the plant-host complex was the stem-borer-injured stem, including the frass produced by the feeding larvae. Moreover, the production of volatiles attractive to a parasitoid was not restricted to the infested stem part but occurs systemically throughout the plant. The uninfested leaves of a stem-borer-infested plant were found to emit volatiles that attract femaleC. flavipes. We further demonstrate that an exogenous elicitor of this systemic plant response is situated in the regurgitate of a stem-borer larva. When a minor amount of regurgitate is inoculated into the stem of an uninfested plant, the leaves of the treated plant emit volatiles that attract femaleC. flavipes.  相似文献   
5.
This paper deals with the problem of piecewise auto regressive systems with exogenous input(PWARX) model identification based on clustering solution. This problem involves both the estimation of the parameters of the affine sub-models and the hyper planes defining the partitions of the state-input regression. The existing identification methods present three main drawbacks which limit its effectiveness. First, most of them may converge to local minima in the case of poor initializations because they are based on the optimization using nonlinear criteria. Second, they use simple and ineffective techniques to remove outliers. Third, most of them assume that the number of sub-models is known a priori. To overcome these drawbacks, we suggest the use of the density-based spatial clustering of applications with noise(DBSCAN) algorithm. The results presented in this paper illustrate the performance of our methods in comparison with the existing approach. An application of the developed approach to an olive oil esterification reactor is also proposed in order to validate the simulation results.  相似文献   
6.
针对高职教育存在不能满足社会人才需求的状况,在分析高职教育自身原因基础上,提出以就业为导向的教学改革思想。以就业为导向的教学,是高职教育追求的目标,是实现人才培养与学生"零距离就业"的根本途径。结合我校近几年软件人才培养模式,总结经验,提出新的以就业为导向培养学生综合能力的教学改革思路,实践证明该教学改革有很好的发展前景。  相似文献   
7.
为了提高氧化铝生产质量和降低能耗,本文分析了氧化铝沉降工艺中影响沉降过程的各种因素,采用小脑模型神经网络(CMAC)系统辨识的方法建立沉降系统的带外部输入的自回归滑移模型(ARMAX)。针对CMAC收敛性存在的问题,提出了基于变步长小脑模型神经网络(CMAC)算法,通过双曲正割函数优化学习步长,提高了小脑模型神经网络算法的收敛速度和计算精度,进而优化了沉降槽密度ARMAX模型。仿真实验表明,该算法的ARMAX模型可以对沉降过程中的槽内密度进行准确识别,指导氧化铝的沉降生产操作。  相似文献   
8.
A multicellular organism is shown to be a community of special self-regulated cells with rigid and flexible regulating links, and a long-term adaptive trend of its system reaction to environmental changes is due to changes in the consumer gradients of groups of cells functioning against the imbalance between synthesis and decay of microstructures. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 136–147, January–February 2008.  相似文献   
9.
货币供应量是货币政策的主要调控指标,在很大程度上影响着股市的波动情况,作者将货币供应量作为外生变量加入到SWARCH模型中,建立了上证指数的考虑外生变量的SWARCH模型,实证研究结果表明该模型具有较好的拟合和预测效果.  相似文献   
10.
The authors propose that there are 2 different mechanisms whereby spatial cues capture attention. The voluntary mechanism is the strategic allocation of perceptual resources to the location most likely to contain the target. The involuntary mechanism is a reflexive orienting response that occurs even when the spatial cue does not indicate the probable target location. Voluntary attention enhances the perceptual representation of the stimulus in the cued location relative to other locations. Hence, voluntary attention affects performance in experiments designed around both accuracy and reaction time. Involuntary attention affects a decision as to which location should be responded to. Because involuntary attention does not change the perceptual representation, it affects performance in reaction time experiments but not accuracy experiments. The authors obtained this pattern of results in 4 different versions of the spatial cuing paradigm. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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