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81.
Kiviniemi VJ Haanpää H Kantola JH Jauhiainen J Vainionpää V Alahuhta S Tervonen O 《Magnetic resonance imaging》2005,23(4):531-537
The blood oxygen level-dependent (BOLD) magnetic resonance signal of functional brain cortices is dominated by very low frequency (VLF) fluctuations in anesthetized child patients. The temporal synchrony of the BOLD signal is also higher in anesthetized children compared with awake adults. The origin of the synchronous fluctuations can be related to maturation, pathological status or the anesthesia used in the imaging. Two of the three confounding variables (maturation and pathology) were controlled in this study. The effect of midazolam (4+/-0.8 mg) sedation on the BOLD signal was assessed in 12 healthy adults (aged 24+/-1.5 years) at 1.5 T. The VLF fluctuation power and temporal synchrony of the BOLD signal increased significantly after the sedation in the auditory and visual cortices. The fast Fourier transformation power spectral baseline fit parameters of the BOLD signal were also found to change significantly after sedation. It is concluded that the VLF fluctuation and temporal synchrony of the BOLD signal become increased after sedation in functional brain regions. 相似文献
82.
83.
This paper investigates the dynamic linkages between stock market prices, accrual earnings and cash flows using Finnish data. We find that stock returns lead accounting returns rather than vice versa. Thus, the thin Finnish stock market appears to produce important information about the future success of Finnish companies for decision making purposes. In addition, the cointegration analysis performed here indicates that the inclusion of the so-called error correction term based on non-stationary price variables significantly improves the observed association between stock market and accounting variables. Thus, in future research, the long-term adjustment between stock market and accounting variables should be analysed more carefully when investigating the causality between accounting earnings and stock markets. 相似文献
84.
A curvilinear internal coordinate Hamiltonian is used to simulate the N-H stretching overtone spectra and the associated inversion splittings in aniline. A simple local mode type model is applied to the N-H stretching and H-N-H bending modes. Geometric algebra is employed to derive the kinetic energy operator for the large amplitude inversion motion. Electronic structure calculations at the Moller-Plesset second order perturbation theory and correlation consistent aug-cc-pVTZ basis set level are used to obtain model parameters, some of which have been optimized with the least-squares method using experimental vibrational term values as data. The observed N-H stretching overtone vibrational levels and the inversional tunneling splittings are well reproduced with our approach. 相似文献
85.
Bobacka J Alaviuhkola T Hietapelto V Koskinen H Lewenstam A Lämsä M Pursiainen J Ivaska A 《Talanta》2002,58(2):341-349
Ion-selective electrodes (ISEs) based on pi-coordinating carriers were prepared and investigated as potentiometric sensors for aromatic cations, using N-methylpyridinium as a model aromatic cation. Derivatives of tetraphenylborate were studied as charged carriers in plasticized poly(vinyl chloride) membranes. Furthermore, neutral compounds containing pi-coordinating anthryl groups were studied as neutral carriers. Bis(2-ethylhexyl)sebacate (DOS) and 2-nitrophenyl octyl ether (o-NPOE) were used as non-polar and polar plasticizer, respectively. ISEs were constructed by using poly(3,4-ethylenedioxythiophene) (PEDOT) as solid-contact material. Conventional ISEs with internal filling solution were used for comparison. The potentiometric responses of the ISEs were investigated using N-methylpyridinium as primary ion. The results show that the selectivity of the ISEs is influenced significantly by both the plasticizer and the charged carriers, while the neutral carriers studied have only a minor influence on the selectivity. The role of cation-pi interactions between aromatic cations and the membrane components is discussed. 相似文献
86.
Russian doll search is applied to finding maximum independent sets in hypergraphs, focusing on a particular subproblem of the hitting set problem, the Steiner triple covering problem. An instance denoted A 135 is solved considerably faster with Russian doll search than with integer linear programming and a state-of-the-art optimization tool (using otherwise a similar established approach to split the problem into subproblems). In addition, the improvement in speed makes it possible to carry out a search proving that all optimal solutions for A 135 are isomorphic. 相似文献