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1.
Aluthge transforms of operators 总被引:7,自引:0,他引:7
Associated with every operatorT on Hilbert space is its Aluthge transform
(defined below). In this note we study various connections betweenT and
, including relations between various spectra, numerical ranges, and lattices of invariant subspaces. In particular, we show that if
has a nontrivial invariant subspace, then so doesT, and we give various applications of our results. 相似文献
2.
ADOLFO V. T. CARTAXO JOÃO L. REBOLA NATAŠA B. PAVLOVIĆ PEDRO M. A. CHARRUA DANIEL D. T. FONSECA JOSÉ A. P. MORGADO 《Fiber and Integrated Optics》2013,32(3-4):331-352
Abstract This article introduces the main achievements resulting from the DWDM/ODC project. The five areas of research activity within the DWDM/ODC project cover some of the main issues of design and development of dense wavelength division multiplexing systems for transparent optical networks. These issues are: performance assessment with arbitrary optical filtering; performance of signaling formats; dispersion compensation strategies for directly and externally modulated systems in presence of nonlinear transmission-induced degradation; and the impact of noise and crosstalk in the extent of transparent optical networks. All five areas of research activity have contributed significantly to a better understanding of the limitations present in dense wavelength division multiplexing systems. 相似文献
3.
A Mukherjee M Dasgupta DJ Hinde CR Morton AC Berriman RD Butt JO Newton H Timmers 《Pramana》2001,57(1):195-198
Fusion cross-sections for the 7Li + 12C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy
evaporation residues with energies below 3 MeV could not be separated out from the α-particles in the spectrum and hence their
contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections
due to the breakup of 7Li may not be significant for 7Li + 12C reaction at energies around the barrier. 相似文献
4.
5.
Jos A Hernndez-Díaz Jorge JO Garza-García Janet M Len-Morales Adalberto Zamudio-Ojeda Jenny Arratia-Quijada Gilberto Velzquez-Jurez Julio C Lpez-Velzquez Soledad García-Morales 《Molecules (Basel, Switzerland)》2021,26(19)
The use of selenium nanoparticles (SeNPs) in the biomedical area has been increasing as an alternative to the growing bacterial resistance to antibiotics. In this research, SeNPs were synthesized by green synthesis using ascorbic acid (AsAc) as a reducing agent and methanolic extract of Calendula officinalis L. flowers as a stabilizer. Characterization of SeNPs was performed by UV-vis spectrophotometry, infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. SeNPs of 40–60 nm and spherical morphologies were obtained. The antibacterial activity of marigold extracts and fractions was evaluated by disk diffusion methodology. The evaluation of SeNPs at different incubation times was performed through the colony-forming unit (CFU) count, in both cases against Serratia marcescens, Enterobacter cloacae, and Alcaligenes faecalis bacteria. Partial antibacterial activity was observed with methanolic extracts of marigold leaves and flowers and total inhibition with SeNPs from 2 h for S. marcescens, 1 h for E. cloacae, and 30 min for A. faecalis. In addition, SeNPs were found to exhibit antioxidant activity. The results indicate that SeNPs present a potentiated effect of both antimicrobial and antioxidant activity compared to the individual use of marigold extracts or sodium selenite (Na2SeO3). Their application emerges as an alternative for the control of clinical pathogens. 相似文献
6.
7.
Ciprian?FoiasEmail author Il?Bong?Jung Eungil?Ko Carl?Pearcy 《Israel Journal of Mathematics》2005,145(1):83-91
We consider the question of which operators on Hilbert space admit a moment sequence, and show, in particular, that ifT is any operator inL(itH) that can be written asT=N+K, whereN is normal andK is compact, andM⊂itH is any invariant subspace forT, then the restrictionT/itM admits such a sequence. 相似文献
8.
可见光响应碳掺杂的光催化剂涂覆于塞流反应器上分解气态芳香化合物(英文) 总被引:1,自引:0,他引:1
A plug‐flow reactor coated with carbon‐doped TiO2 (C‐TiO2 ) powder was investigated for the control of vaporous aromatics (benzene, toluene, ethylbenzene, and o‐xylene (BTEX)) under a range of experimental conditions. The characteristics of the as‐prepared C‐TiO2 and a reference Degussa P25 TiO2 powder were examined using X‐ray diffraction, scanning electron microscopy, diffuse‐reflectance ultraviolet‐visible‐near infrared spectroscopy, and Fourier transform infrared spectroscopy. The experimental conditions for the photocatalytic performance of the as‐prepared C‐TiO2 photocatalyst were controlled using three operational parameters, relative humidity, flow rate, and input concentration. Unlike other target compounds, very little benzene was removed by the C‐TiO2 photocatalyst under visible‐light irradiation. In contrast, the C‐TiO2 exhibited higher removal efficiencies for the other three target compounds (toluene, ethylbenzene, and xylene) compared with those achieved using unmodified TiO2 under visible‐light irradiation. The highest removal efficiency was obtained at a relative humidity value of 45%. Specifically, the toluene removal efficiency determined at a relative humidity of 45% was 78%, whereas it was close to 0%, 7.2%, and 5.5% for relative humidity values of 20%, 70%, and 95%, respectively. In addition, the removal efficiencies for the three target compounds decreased as the flow rate or input concentration increased. These findings indicate that the as‐prepared C‐TiO2 photocatalyst could be used for the removal of toxic vaporous aromatics under optimized operating conditions. 相似文献
9.
C. Foias I. B. Jung E. Ko C. Pearcy 《Transactions of the American Mathematical Society》2007,359(6):2899-2913
In this article we employ a technique originated by Enflo in 1998 and later modified by the authors to study the hyperinvariant subspace problem for subnormal operators. We show that every ``normalized'subnormal operator such that either does not converge in the SOT to the identity operator or does not converge in the SOT to zero has a nontrivial hyperinvariant subspace.
10.
A. B. LOBO RIBEIRO J. L. SANTOS J. M. BAPTISTA L. A. FERREIRA F. M. ARAÚJO A. P. LEITE 《Fiber and Integrated Optics》2013,32(3-4):171-199
Abstract A general overview of the R&D activity in fiber optic sensing developed over the last fifteen years in Portugal is given. Different topics are addressed, including interferometric, intensity and Bragg grating based fiber optic sensors, signal processing and multiplexing techniques, optical current sensors, together with some references to field trials and applications. Possible guidelines for present and future national R&D activity on this subject are outlined. 相似文献