20,063 research outputs found
WhatIF: R Software for Evaluating Counterfactuals
No full textWhatIf is an R package that implements the methods for evaluating counterfactuals introduced in King and Zeng (2006a) and King and Zeng (2006b). It offers easy-to-use techniques for assessing a counterfactual's model dependence without having to conduct sensitivity testing over specified classes of models. These same methods can be used to approximate the common support of the treatment and control groups in causal inference.
CENP-G in neocentromeres and inactive centromeres
No full textCENP-G is a novel constitutive centromere-specific protein localized to the kinetochore inner plate and subjacent region. It has been identified as associating specifically with the α-1 subfamily of α-satellite DNA. In the present work, the localization of CENP-G was compared with that of other CENPs by immunofluorescence and fluorescence in situ hybridization. Studies were carried out on four abnormal human centromeres:
two neocentromeres and two inactive centromeres.
CENP-G was detected in one of the two inactive centromeres but not in the other that shows a partial deletion of the alphoid DNA. Interestingly, CENP-G is also present in neocentromeres, which lack alphoid DNA sequences, and in the human Y chromosome, which lacks the α-1 type of satellite DNA. These data provide further evidence that CENP-G may be an essential factor in cen-
tromeric function and that in centromeres lacking the α-1 subfamily of alphoid DNA, other DNA sequences are able to bind CENP-G
Optimal beaconing control for epidemic routing in delay tolerant networks
No full textOwing to the uncertainty of transmission opportunities between mobile nodes, the routing in delay-tolerant networks (DTNs) exploits the mechanism of opportunistic forwarding. Energy-efficient algorithms and policies for DTN are crucial to maximizing the message delivery probability while reducing the delivery cost. In this contribution, we investigate the problem of energy-efficient optimal beaconing control in a DTN. We model the message dissemination under variable beaconing rate with a continuous-time Markov model. Based on this model, we then formulate the optimization problem of the optimal beaconing control for epidemic routing and obtain the optimal threshold policy from the solution of this optimization problem. Furthermore, through extensive numerical results, we demonstrate that the proposed optimal threshold policy significantly outperforms the static policy with constant beaconing rate in terms of system energy consumption savings
Removing spurious interactions in complex networks
No full textIdentifying and removing spurious links in complex networks is meaningful for many real applications and is crucial for improving the reliability of network data, which, in turn, can lead to a better understanding of the highly interconnected nature of various social, biological, and communication systems. In this paper, we study the features of different simple spurious link elimination methods, revealing that they may lead to the distortion of networks’ structural and dynamical properties. Accordingly, we propose a hybrid method that combines similarity-based index and edge-betweenness centrality. We show that our method can effectively eliminate the spurious interactions while leaving the network connected and preserving the network's functionalities
Bias Correction in Logarithmic Regression and Comparison with Weighted Regression for Nonlinear Models
No full textNon-linear models with heteroscedasticity are commonly used in ecological and forestry modeling, and logarithmic regression and weighted regression are usually employed to estimate the parameters. Using the single-tree biomass data of three large samples, the bias correction in logarithmic regression for non-linear models was studied and comparison between logarithmic regression and weighted regression was discussed in this paper. Firstly, the imminent cause producing bias in logarithmic regression was analyzed, and a new correction factor was presented with which three commonly used bias correction factors were examined together, and the results showed that the correction factors presented here and derived by Baskerville (1972) should be recommended, which could insure the corrected model to be asymptotically consistent with that fitted by weighted regression. Secondly, the fitting results of weighted regression for non-linear models, using the weight function based on residual errors of the model estimated by ordinary least squares (OLS) and the general weight function (w=1/ƒ(x)2) presented by Zeng (1998) respectively, were compared with each other that showed two weight functions worked well and the general function was more applicable. It was suggested that the best way to fit non-linear models with heteroscedasticity would be using weighted regression, and if the total relative error of the estimates from the model fitted by the general weight function was more than a special allowance such as ±3%, a better weight function based on residual errors of the model fitted by OLS should be used in weighted regression
New and noteworthy boletes from subtropical and tropical China
No full textThe morphology, ecology, and phylogenetic relationships of specimens of the family Boletaceae from subtropical and tropical China were investigated. Four species, Butyriboletus huangnianlaii, Lanmaoa macrocarpa, Neoboletus multipunctatus, and Sutorius subrufus, are new to science. Chalciporus radiatus and Caloboletus xiangtoushanensis are redescribed. Caloboletus guanyui is proposed to replace Boletus quercinus Hongo, an illegitimate later homonym. The recently described Tylopilus callainus is synonymized with the Japanese Boletus virescens, and the new combination T. virescens (Har. Takah. & Taneyama) N.K. Zeng et al. is proposed. Moreover, Neoboletus is treated as an independent genus based on evidence from morphology and molecular phylogenetic data in the present study, and many previously described taxa of Sutorius are recombined into Neoboletus: N. ferrugineus (G. Wu et al.) N.K. Zeng et al., N. flavidus (G. Wu & Zhu L. Yang) N.K. Zeng et al., N. hainanensis (T.H. Li & M. Zang) N.K. Zeng et al., N. obscureumbrinus (Hongo) N.K. Zeng et al., N. rubriporus (G. Wu & Zhu L. Yang) N.K. Zeng et al., N. sanguineoides (G. Wu & Zhu L. Yang) N.K. Zeng et al. , N. sanguineus (G. Wu & Zhu L. Yang) N.K. Zeng et al., and N. tomentulosus (M. Zang et al.) N.K. Zeng et al
Data for: Monitoring the global evolution of the storm-ring current and the storm indices from confined ground geomagnetic observatories
No full textThe data files contain the results deduced from our method by eastern stations and global stations on the 4-8 October 2000, 25-28 October 2007 and 7-11 November 2004 storms. The data files also contain the storm indices deduced from our method by three local stations and six global stations prior to 1957
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