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71.
Identification of human brain structures in MR images comprises an area of increasing interest, which also presents numerous methodological challenges. Here we describe a new knowledge-based automated method designed to identify several major brain sulci and then to define the frontal lobes by using the identified sulci as landmarks. To identify brain sulci, sulcal images were generated by morphologic operations and then separated into different components based on connectivity analysis. Subsequently, the individual anatomic features were evaluated by using fuzzy membership functions. The crisp decisions, i.e., the identification of sulci, were made by taking the maximum of the summation of all the membership functions. The identification was designed in a hierarchical order. The longitudinal fissure was extracted first. The left and right central sulci were then identified based on the left and right hemispheres. Next, the lateral sulci were identified based on the central sulci and hemispheres. Finally, the left and right frontal lobes were defined from the two hemispheres. The method was evaluated by visual inspection, comparison with manual segmentation, and comparison with manually volumetric results in references. The average Jaccard similarities of left and right frontal lobes between the automated and manual segmentation were 0.89 and 0.91, respectively. The average Kappa indices of left and right frontal lobes between the automated and manual segmentation were 0.94 and 0.95, respectively. These results show relatively high accuracy of using this novel method for human frontal lobe identification and segmentation. 相似文献
72.
Guo-Ping Li Yun-Gang Zhou Xiao-Tao Zu 《International Journal of Theoretical Physics》2013,52(11):4025-4031
Applying the Hamilton-Jacobi method, we investigate particles’ tunneling behavior in a spherically symmetric spacetime with dark matter. The tunneling rate and Hawking temperature at the event horizon are obtained. The result shows that the dark matter parameter β has an important influence on the Hawking temperature and the tunneling rate. 相似文献
73.
Zu‐Shun Xu Zi‐Wei Deng Xiao‐Xi Hu Lei Li Chang‐Feng Yi 《Journal of polymer science. Part A, Polymer chemistry》2005,43(11):2368-2376
Monodisperse polystyrene microspheres with diameters of 200–500 nm were prepared by dispersion polymerization with microwave irradiation with poly(N‐vinylpyrrolidone) as a steric stabilizer and 2,2′‐azobisisobutyronitrile as a radical initiator in an ethanol/water medium. The morphology, size, and size distribution of the polystyrene microspheres were characterized with transmission electron microscopy and photon correlation spectroscopy, and the formed films of the polystyrene dispersions were characterized with atomic force microscopy. The effects of the monomer concentration, stabilizer concentration, and initiator concentration on the size and size distribution of the polystyrene microspheres were investigated. The polystyrene microspheres prepared by dispersion polymerization with microwave irradiation were smaller, more uniform, and steadier than those obtained with conventional heating. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2368‐2376, 2005 相似文献
74.
75.
VALUE-AT-RISK的核估计理论 总被引:5,自引:0,他引:5
如何根据历史数据估计Value-at-Risk(VaR);是风险分析与管理中一个重要的基本问题.木文基于非参数核估计方法,通过拟合实际数据过程的分布,构造了VaR的估计.在合适的相依数据条件下,证明了该估计量的渐近正态性,并给出了渐近方差的估计.由此表明:本文所构造的估计量不仅比参数模型具有更广泛的适应性,而且如同参数模型具有n~(-1/2)的收敛速度.本文假设的数据过程避免使用混合性,可很好地适用于金融管理中广泛应用的ARMA与GARCH模型族及非线性模型. 相似文献
76.
讨论了目前有关22Na(p,γ)23Mg反应的实验研究工作,结合兰州放射性束流线上的放射性束流23Al的β+延发质子衰变实验的测量结果,给出了23Al延发衰变的质子能谱,并比较了近期实验给出的相关能级的自旋、宇称值,正是由于这种自旋、宇称和能级部分宽度的不确定性,导致了反应率计算的不确定性.计算了同位旋相似态的共振强度.对于测量到的新的延发衰变能级Ed=8.916MeV,由于没有相应的能级宽度值,实验仅给出其相对共振强度值. 相似文献
77.
DelphiniumsoulieiFranch,distributedintheSouthwestofGansuProvince,WestofSichuanProvince,andtheQinghaiProvinceofChina,isreportedtopossessantipyretic,antitoxic,antidysenteric,andantidiarrhealactivities.linthisstUdy,twonewditerpenoidalkaloidswereisolatedfromthewholeplantsofD.soulidi.TheirstructUreswereestablishedassoulineA(l)andsoulineB(2)onthebasisofspectraldata.SoulineA(l)wasisolatedascolorlesscrystals.Themolecularionpeakatm/z477.2678initsHREIMSrevealedthemolecularformulaC26H39NO7(cafe… 相似文献
78.
IrnmobilisedaIninoacylaseisanotablecatalystforthekineticresolutionofN-acetyl-D,L-aIninoacidsandquitealotofresearchworkhasbeeninvolvedonaminoacylase~bilisationswithitscarriers.lTheauthorshaverePortedthattheaIninosilicagelspreparedbyanlinProvedmethodwereeffechveforchymotryPsininunobilisahon,'l'butitwasnotproperforaIninoacylasetriobilisahon.InordertodevelopasahsfactorysurfacesmictUreofsilicagelsforaIninoacylasetriobilisation,tWokindsofreactivegrouPs,theN,N-diethylaIninogrouPandthehydroxygr… 相似文献
79.
Photonic band structures of two-dimensional photonic crystals with deformed lattices 总被引:2,自引:0,他引:2 下载免费PDF全文
Using the plane-wave expansion method, we have calculated and analysed the
changes of photonic band structures arising from two kinds of deformed
lattices, including the stretching and shrinking of lattices. The square
lattice with square air holes and the triangular lattice with circular air
holes are both studied. Calculated results show that the change of lattice
size in some special ranges can enlarge the band gap, which depends strongly
on the filling factor of air holes in photonic crystals; and besides, the
asymmetric band edges will appear with the broken symmetry of lattices. 相似文献
80.