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We employ an optimal solution to both the shape from motion problem and the related problem of the estimation of self-movement on a purely optical basis to deduce practical rules of thumb for the limits of the optic flow information content in the presence of perturbation of the motion parallax field. The results are illustrated and verified by means of a computer simulation.The results allow estimates of the accuracy of depth and egomotion estimates as a function of the accuracy of data sampling and the width of field of view, as well as estimates of the interaction between rotational and translational components of the movement. 相似文献
225.
Representation of local geometry in the visual system 总被引:10,自引:0,他引:10
226.
Linkage relationship between the genes for adenosine deaminase and S-adenosyl-homocysteine hydrolase on human chromosome 20 总被引:2,自引:0,他引:2
Summary The genes for adenosine deaminase (ADA) and Sadenosyl homocysteine hydrolase (AHCY or SAHH) are known to be syntenic and within
measurable distance from each other, on chromosome 20 in man. In the present study an informative family is described in which
the recombination fraction (θ) between the respective genes is estimated to be about 0.18. Together with the published finding
of θ=0.15 (Eiberg and Mohr 1985) in informative Danish families, the recombination fraction for the pooled data is calculated
to be θ=0.14 (in men),
(in women) and
(both sexes taken together). 相似文献
227.
An interstitial duplication of the X chromosome in a male allows physical fine mapping of probes from the Xq13-q22 region 总被引:8,自引:2,他引:6
F. P. M. Cremers R. A. Pfeiffer T. J. R. van de Pol M. H. Hofker T. A. Kruse B. Wieringa H. H. Ropers 《Human genetics》1987,77(1):23-27
Summary An insertional translocation into the proximal long arm of the X chromosome in a boy showing muscular hypotony, growth retardation, psychomotor retardation, cryptorchidism, and Pelizaeus-Merzbacher disease (PMD) was identified as a duplication of the Xq21–q22 segment by employing DNA probes. With densitometric scanning for quantitation of hybridization signals, 15 Xq probes were assigned to the duplicated region. Analysis of the duplication allowed us to dissect the X-Y homologous region physically at Xq21 and to refine the assignments of the loci for DXYS5, DXYS12, DXYS13, DXS94, DXS95, DXS96, DXS111, and DXS211. Furthermore, we demonstrated the presence of two different DXYS13, and DXS17 alleles in genomic DNA of our patient, suggesting that the duplication resulted from a meiotic recombination event involving the two maternal X chromosomes. 相似文献
228.
Conformational analysis of a cyclic thymopoietin-analogue by 1H n.m.r. spectroscopy and restrained molecular dynamics simulations 总被引:1,自引:0,他引:1
J Lautz H Kessler R Boelens R Kaptein W F van Gunsteren 《International journal of peptide and protein research》1987,30(3):404-414
The internuclear distances of the cyclic thymopoietin derivative c[D-Val-Tyr-Arg-Lys-Glu] have been determined using two-dimensional nuclear Overhauser n.m.r. spectroscopy. These distances are used as constraints for a restrained Molecular Dynamics (MD) simulation. The two starting structures used for the calculations consist of a beta and gamma turn for model 1 and two gamma turns for model 2. The rms difference in atomic positions of the two conformations is 0.242 nm. They converge during the restrained MD simulation to the same final structure. The positional rms difference of the time averaged (5-14 ps) conformations is 0.011 nm. The hydrogen bond pattern is similar to that of model 1, but in addition we find three more gamma turns. The vicinal NH-C alpha H couplings agree well with those calculated from the time averaged structures. 相似文献
229.
230.
Effects of lethal exposure to hyperoxia and to hydrogen peroxide on NAD(H) and ATP pools in Chinese hamster ovary cells 总被引:1,自引:0,他引:1
Cell death by oxidative stress has been proposed to be based on suicidal NAD depletion, typically followed by ATP depletion, caused by the NAD-consuming enzyme poly(ADP)ribose polymerase, which becomes activated by the presence of excessive DNA-strand breaks. In this study NAD+, NADH and ATP levels as well as DNA-strand breaks (assayed by alkaline elution) were determined in Chinese hamster ovary (CHO) cells treated with either H2O2 or hyperoxia to a level of more than 80% clonogenic cell killing. With H2O2 extensive DNA damage and NAD depletion were observed, while at a higher H2O2 dosage ATP also became depleted. In agreement with results of others, the poly(ADP)ribose polymerase inhibitor 3-aminobenzamide completely prevented NAD depletion. However, both H2O2-induced ATP depletion and cell killing were unaffected by the inhibitor, suggesting that ATP depletion may be a more critical factor than NAD depletion in H2O2-induced killing of CHO cells. With hyperoxia, only moderate DNA damage (2 X background) and no NAD depletion were observed, whereas ATP became largely (70%) depleted. We conclude that (1) there is no direct relation between ATP and NAD depletion in CHO cells subjected to toxic doses of H2O2 or hyperoxia; (2) H2O2-induced NAD depletion is not by itself sufficient to kill CHO cells; (3) killing of CHO cells by hyperoxia is not due to NAD depletion, but may be due to depletion of ATP. 相似文献