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961.
Weis J Ahlström H Hlavcak P Häggman M Ortiz-Nieto F Bergman A 《Magnetic resonance imaging》2009,27(1):87-93
Purpose
To minimize user and vendor dependence of the spectrum processing of prostate spectra, to measure the ratio of choline (Cho) plus creatine (Cr) to citrate (Cit) in the prostate tissue of normal volunteers and cancer patients, and to compare the results with pathologic findings after radical prostatectomy.Materials and methods
Four healthy volunteers and 13 patients with prostate cancer were measured. Measurements were performed using two-dimensional magnetic resonance spectroscopic imaging (MRSI) and endorectal coil. A standard vendor's spectrum processing approach has been modified. An original feature of this methodology was the combination of vendor-optimized and user-independent spectrum preprocessing in the scanner and user-independent quantitation in the environment of an MRUI software package. (Cho+Cr)/Cit ratio was used for the classification of prostate tissue. Results were compared with histopathology after radical prostatectomy.Results
Eight of 13 cancer patients were classified as suspicious or very suspicious for cancer at spectroscopy, three were ambiguous for cancer and two patients were evaluated as false negative. A considerable overlap of metabolite ratios at various Gleason score was found.Conclusion
The proposed spectrum processing has the potential to improve the accuracy and user independency of the (Cho+Cr)/Cit quantitation. This study confirmed the previous results that a considerable overlap of (Cho+Cr)/Cit ratios exists at various Gleason score levels. 相似文献962.
A.Martínez Torres 《中国物理C(英文版)》2009,33(12)
We have studied the ππN system and coupled channels by using of the Faddeev equations and two N~* and one △ states, all of them with J~P = 1/2~+, have been found in the formalism as dynamically generated states. In addition, signatures for a new N* resonance with J~P = 1/2~+ are found around an energy of 1920 MeV in the three-body center of mass system. 相似文献
963.
Francisco Javier González Javier Alda Jorge Simón James Ginn Glenn Boreman 《Infrared Physics & Technology》2009,52(1):48-51
In this paper the optical parameters at infrared frequencies of metallic thin films were obtained experimentally using a variable angle spectroscopic ellipsometer and used to simulate numerically the frequency response of antennas and antenna-coupled detectors at infrared frequencies (5–15 μm). The simulation results agree with previously published data and practical guidelines are presented for the design and fabrication of dipole and bowtie antennas at infrared frequencies. 相似文献
964.
A.?Martínez Torres K.?P.?Khemchandani U.?-G.?Mei?ner E.?Oset 《The European Physical Journal A - Hadrons and Nuclei》2009,41(3):361-368
We provide a series of arguments which support the idea that the peak seen in the \( \gamma\) p \( \rightarrow\) K + \( \Lambda\) reaction around 1920MeV should correspond to the recently predicted state of J P = 1/2+ as a bound state of K \( \bar{{K}}\) N with a mixture of a 0(980)N and f 0(980)N components. At the same time we propose polarization experiments in that reaction as a further test of the prediction, as well as a study of the total cross-section for \( \gamma\) p \( \rightarrow\) K + K - p at energies close to threshold and of dσ/dM inv for invariant masses close to the two-kaon threshold. 相似文献
965.
This paper presents a numerical study of magnetization switching driven by spin-polarized current in high-TMR magnetic tunnel junctions (TMR>100%). The current density distribution throughout the free-layer is computed dynamically, by modeling the ferromagnet/insulator/ferromagnet trilayer as a series of parallel resistances. The validity of the main hypothesis, which states that the current flows perpendicular to the sample plane, has been verified by numerically solving the Poisson equation. Our results show that the nonuniform current density distribution is a source of asymmetry to the switching process. Furthermore, we observe that the reversal mechanisms are characterized by well-defined localized pre-switching oscillation modes. 相似文献
966.
967.
We show that the Ginzburg-Landau expansion of the grand potential for the Bogoliubov-de Gennes Hamiltonian is determined by the integrable nonlinear equations of the AKNS hierarchy, and that this provides the natural mathematical framework for a hidden nonlinear quantum mechanical supersymmetry underlying the dynamics. 相似文献
968.
969.
Jose G. Trujillo‐Ferrara Efrn V. García‐Bez Itzia I. Padilla‐Martínez Francisco J. Martínez‐Martínez Norberto Farfan‐García 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(6):o427-o430
In exo‐2‐(3,5‐dioxo‐10‐oxa‐4‐azatricyclo[5.2.1.02,6]dec‐8‐en‐4‐yl)phenyl acetate, C16H13NO5, the plane of the acetoxy group lies almost perpendicular to that of the phenyl ring [dihedral angle = 89.8 (1)°], in contrast with the smaller deviations found in the para isomer exo‐4‐(3,5‐dioxo‐10‐oxa‐4‐azatricyclo[5.2.1.02,6]dec‐8‐en‐4‐yl)phenyl acetate, C16H13NO5, these being 63.6 (1) and 37.0 (1)° for the two crystallographically independent molecules. Irrespective of the position of the acetoxy group, both compounds pack through soft C—H⋯X (X is O or phenyl) interactions, forming interlinked centrosymmetric tetramers in the bc plane. 相似文献
970.
Mechanical recycling of poly(ethylene terephthalate) (PET) was simulated by multiple processing to assess the effects of thermo-mechanical degradation, and characterized using rheological and thermal analysis techniques. Thermo-mechanical degradation under repeated extrusion induces chain scission reactions in PET, which result in a dramatic loss in the deformation capabilities and an increase in the fluidity of the polymer under reprocessing, reducing its recycling possibilities after four extrusion cycles. Multiple reprocessing severely affects the storage modulus and the microstructure of recycled PET, both in the amorphous and crystalline regions. Multimodal melting behavior is observed for reprocessed PET, indicating heterogeneous and segregated crystalline regions. A deconvolution procedure has been applied to individually characterize each crystalline population in terms of lamellar thickness distribution and partial crystallinity. Thermal analysis techniques such as differential scanning calorimetry (DSC) and dynamic-mechanical analysis (DMA) have proved to be suitable techniques for the quality assessment of recycled PET, giving unequivocal information about its degree of degradation compared to the common technological measurements of melt-mass flow rate (MFR) or oxidative stability (TOx). 相似文献