Abstract：
:We have developed a new two-step algorithm to determine the astigmatism of images from transmission electron microscopes (TEMs). Instead of computing the radial average of the power spectrum, we divide the power spectrum of a TEM image 1 to m (typically 32) sectors. We use a technique based on perturbation analysis of the contrast transfer function (CTF) to assimilate sector averages of the power spectrum of an image, which are incoherent in the presence of astigmatism, to a coherent radial average corresponding to a nominal defocus value. This is based on the fact that small defocus change from a nominal value can be considered to be equivalent to a perturbation on the spatial frequency spectra. Thus, instead of measuring the angular defocus variations, we optimise the frequency change required to obtain a coherent radial average. Numerically, this is achieved by minimizing sigma(2)/sigma(1) of a matrix formed from the sector averages, where sigma(i) denotes the ith singular value of the matrix. After the minimisation procedure, the second singular value should be very small compared with the first singular value, indicating that the matrix is nearly rank unity. In the second step, the nominal defocus can be obtained from the coherent radial average using any good defocus estimation program, which assumes zero astigmatism. The defocus value at a sector can be obtained from this nominal defocus value and one of the parameters from the unconstrained optima. Our algorithm is tested on astigmatic images of carbon film, 2D crystals of bacteriorhodopsin and cryo-images of HIV cores.
journal_name
J Struct Bioljournal_title
Journal of structural biologyauthors
Fernando KV,Fuller SDdoi
10.1016/j.jsb.2006.07.021subject
Has Abstractpub_date
2007-01-01 00:00:00pages
189-200issue
1eissn
1047-8477issn
1095-8657pii
S1047-8477(06)00208-5journal_volume
157pub_type
杂志文章abstract：:The baculum is an extraskeletal bone located in the penis of a few species in several orders of mammals such as carnivores, insectivores, rodents, bats and primates. This study aims to describe the structure, architecture and mechanical properties of the canine baculum. To this end canine bacula from castrated and unc...
journal_title：Journal of structural biology
pub_type： 杂志文章
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更新日期：2011-09-01 00:00:00
abstract：:We have developed a simplified, efficient approach for the 3D reconstruction and analysis of mammalian cells in toto by electron microscope tomography (ET), to provide quantitative information regarding 'global' cellular organization at approximately 15-20 nm resolution. Two insulin-secreting beta cells-deemed 'functi...
journal_title：Journal of structural biology
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journal_title：Journal of structural biology
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/s1047-8477(02)00560-9
更新日期：2002-08-01 00:00:00
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pub_type： 杂志文章
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/j.jsb.2011.11.019
更新日期：2012-02-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/j.jsb.2010.03.006
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journal_title：Journal of structural biology
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doi：10.1006/jsbi.1999.4163
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/j.jsb.2009.07.023
更新日期：2010-01-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1006/jsbi.2002.4438
更新日期：2002-01-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1006/jsbi.1997.3864
更新日期：1997-07-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/j.jsb.2018.05.008
更新日期：2018-09-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
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更新日期：2020-01-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1006/jsbi.1994.1029
更新日期：1994-07-01 00:00:00
abstract：:Computational modeling of membrane proteins is critical to understand biochemical systems and to support chemical biology. In this work, we use a dataset of 448 non-redundant membrane protein chains to expose a "rule" that governs membrane protein structure: free cysteine thiols are not found accessible to oxidative c...
journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/j.jsb.2019.10.002
更新日期：2020-01-01 00:00:00
abstract：:The recombinant dihydropyrimidinase from Sinorhizobium meliloti CECT4114 (SmelDhp) has been characterised and its crystal structure elucidated at 1.85A. The global architecture of the protein is reminiscent of that of the amidohydrolase superfamily, consisting of two domains; an (alpha/beta)(8) TIM-like barrel domain,...
journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/j.jsb.2009.10.013
更新日期：2010-02-01 00:00:00
abstract：:By taking advantage of network-based computing and the recent developments in Web interfaces, centralized research facilities housing specialized and unique imaging instruments along with associated high-performance computing can be made available to researchers for use from their own laboratories. In addition to incr...
journal_title：Journal of structural biology
pub_type： 杂志文章,评审
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更新日期：1999-04-01 00:00:00
abstract：:Long-depth imaging of specific gene expression in the midgestation whole-mount mouse embryo (WME) is demonstrated with single-photon excitation (1PE) confocal fluorescence microscopy and fluorescence in situ hybridization. Expression domains of Pax-6 mRNA transcripts were labeled with an in situ hybridization probe th...
journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1006/jsbi.2000.4238
更新日期：2000-07-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/s1047-8477(02)00574-9
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journal_title：Journal of structural biology
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更新日期：2005-03-01 00:00:00
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journal_title：Journal of structural biology
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doi：10.1016/j.jsb.2019.06.003
更新日期：2019-09-01 00:00:00
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journal_title：Journal of structural biology
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doi：10.1016/j.jsb.2008.09.009
更新日期：2009-01-01 00:00:00
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doi：10.1016/j.jsb.2012.04.012
更新日期：2012-07-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
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更新日期：2016-12-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
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更新日期：2016-12-01 00:00:00
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更新日期：2020-10-01 00:00:00
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journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/j.jsb.2010.06.022
更新日期：2010-12-01 00:00:00
abstract：:The Bsoft package is aimed at processing electron micrographs for the determination of the three-dimensional structures of biological specimens. Recent advances in hardware allow us to solve structures to near atomic resolution using single particle analysis (SPA). The Map Challenge offered me an opportunity to test t...
journal_title：Journal of structural biology
pub_type： 杂志文章
doi：10.1016/j.jsb.2018.07.003
更新日期：2018-10-01 00:00:00
