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排序方式: 共有196条查询结果,搜索用时 281 毫秒
111.
Salla-Maarit Kokkonen Juha Nikkinen Jukka Remes Jussi Kantola Tuomo Starck Marianne Haapea Juho Tuominen Osmo Tervonen Vesa Kiviniemi 《Magnetic resonance imaging》2009
Analysis of resting-state functional magnetic resonance imaging (fMRI) data is based on detecting low-frequency signal fluctuations in functionally connected brain areas. These synchronous fluctuations in resting-state networks have been observed in several studies with healthy subjects. In this study, we explored if independent component analysis (ICA) can be used to localize the sensorimotor area from resting-state fMRI data in patients with brain tumors. Finger-tapping activation task and resting-state blood-oxygenation-level-dependent fMRI data were acquired from 8 patients with brain tumors and 10 healthy volunteers. Sensorimotor task independent components (ICtask) were used to verify resting-state independent components (ICrest) individually. In addition, sensorimotor ICrests were compared between the groups and no significant differences were detected in volume, spatial correlation or temporal correlation. These results show that it is possible to localize a sensorimotor area from resting-state data using ICA in patients with brain tumors. This offers a complementary method for assessing the sensorimotor area in subjects with brain tumors who have difficulties in performing motor paradigms. 相似文献
112.
Distortion functions for plane quasiconformal mappings 总被引:2,自引:0,他引:2
The authors study two well-known distortion functions, λ(K) andϕ
K(r), of the theory of plane quasiconformal mappings and obtain several new inequalities for them. The proofs make use of some
properties of elliptic integrals.
The work of the first author was supported in part by a grant from the United States National Science Foundation. The work
of the first and second authors was supported in part by a grant from the Academy of Finland. 相似文献
113.
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115.
In general correlated models, in addition to the usual adiabatic component with a spectral index n(ad1) there is another adiabatic component with a spectral index n(ad2) generated by entropy perturbation during inflation. We extend the analysis of a correlated mixture of adiabatic and isocurvature cosmic microwave background fluctuations of the Wilkinson Microwave Anisotropy Probe (WMAP) group, who set the two adiabatic spectral indices equal. Allowing n(ad1) and n(ad2) to vary independently we find that the WMAP data favor models where the two adiabatic components have opposite spectral tilts. Using the WMAP data only, the 2sigma upper bound for the isocurvature fraction f(iso) of the initial power spectrum at k(0)=0.05 Mpc(-1) increases somewhat, e.g., from 0.76 of n(ad2)=n(ad1) models to 0.84 with a prior n(iso)<1.84 for the isocurvature spectral index. 相似文献
116.
Vuorinen JE Schwarz RB McCullough C 《The Journal of the Acoustical Society of America》2000,108(2):574-579
The five independent second-order elastic constants of a transversely isotropic aluminum/alumina fiber composite have been measured for the first time using a resonant ultrasound spectroscopy technique. These data were used to deduce the elastic constants and engineering moduli for off-axis loading conditions. 相似文献
117.
Vesa Vuorinen Tomi Laurila Toni Mattila Erkki Heikinheimo Jorma K. Kivilahti 《Journal of Electronic Materials》2007,36(10):1355-1362
Solid-state interfacial reactions between Sn and Cu(Ni) alloys have been investigated at the temperature of 125°C. The following
results were obtained. Firstly, the addition of 0.1 at.% Ni to Cu decreased the total thickness of the intermetallic compound
(IMC) layer to about half of that observed in the␣binary Cu/Sn diffusion couple; the Ni addition decreased especially the
thickness of Cu3Sn. Secondly, the addition of 1 to 2.5 at.% Ni to Cu further decreased the thickness of Cu3Sn, increased that of Cu6Sn5 (compared to that in the binary Cu/Sn couple) and produced significant amount of voids at the Cu/Cu3Sn interface. Thirdly, the addition of 5 at.% Ni to Cu increased the total thickness of the IMC layer to about two times that
observed in the binary Cu/Sn diffusion couple and made the Cu3Sn disappear. Fourthly, in contrast to the previous case, the addition of 10 at.% Ni to Cu decreased the total IMC (Cu6Sn5) thickness again close to that of the Cu/Sn couple. With this Ni content no voids were detected. The results are rationalized
with the help of␣the thermodynamics of the Sn-Cu-Ni system as well as with kinetic considerations. 相似文献
118.
Marco?BarchiesiEmail author Vesa?Julin 《Calculus of Variations and Partial Differential Equations》2017,56(3):80
We provide a sharp quantitative version of the Gaussian concentration inequality: for every \(r>0\), the difference between the measure of the r-enlargement of a given set and the r-enlargement of a half-space controls the square of the measure of the symmetric difference between the set and a suitable half-space. We also prove a similar estimate in the Euclidean setting for the enlargement with a general convex set. This is equivalent to the stability of the Brunn–Minkowski inequality for the Minkowski sum between a convex set and a generic one. 相似文献
119.
Lehtonen HM Penttinen H Rauhala J Välimäki V 《The Journal of the Acoustical Society of America》2007,122(3):1787
This paper describes the main features of the sustain-pedal effect in the piano through signal analysis and presents an algorithm for simulating the effect. The sustain pedal is found to increase the decay time of partials in the middle range of the keyboard, but this effect is not observed in the case of the bass and treble tones. The amplitude beating characteristics of piano tones are measured with and without the sustain pedal engaged, and amplitude envelopes of partial overtone decay are estimated and displayed. It is found that the usage of the sustain pedal introduces interesting distortions of the two-stage decay. The string register response was investigated by removing partials from recorded tones; it was observed that as the string register is free to vibrate, the amount of sympathetic vibrations is increased. The synthesis algorithm, which simulates the string register, is based on 12 string models that correspond to the lowest tones of the piano. The algorithm has been tested with recorded piano tones without the sustain pedal. The objective and subjective results show that the algorithm is able to approximately reproduce the main features of the sustain-pedal effect. 相似文献
120.
Arja Sarpola Heikki Hellman Vesa Hietapelto Jorma Jalonen Jukka Jokela Jaakko Rämö Jaakko Saukkoriipi 《Polyhedron》2007
Hydrolysis and speciation of aluminium sulfate octadecahydrate Al2(SO4)3·18H2O was studied by electrospray time of flight mass spectrometry (ESI TOF MS). Several novel polymeric species were determined. Highly charged polymers, characterized by other methods, such as the Keggin cation [Al13O4(OH)24(H2O)12]7+ and the octameric aluminium hydroxide cluster [Al8(OH)14(H2O)18](SO4)5 16H2O, were found using ESI-MS as the anions [Al13O4(OH)25(SO4)4]2− and [Al8O(OH)14(SO4)5(H2O)4]2−. All the main species identified contained sulfate or hydrogen sulfate. The compositions of the determined ions mimicked those of several stable mineral forms. 相似文献