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Very Sharp (very + sharp)
Selected AbstractsZinc Oxide Microtowers by Vapor Phase Homoepitaxial RegrowthADVANCED MATERIALS, Issue 8 2009Zhengwei Pan Simultaneous axial and radial epitaxies can be achieved on growing ZnO microtowers through a regrowth technique of repeating the same growth circle for several times. The as-grown ZnO microtowers display a preferential growth habit of hexagonal prism,dihexagonal pyramid. The apexes of the pyramidal towers are very sharp, with a radius of curvature as small as 2 to 50 nm. [source] High-field MRSI of the prostate using a transmit/receive endorectal coil and gradient modulated adiabatic localizationJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2009Jamie Near PhD Abstract Purpose To demonstrate in vivo magnetic resonance spectroscopic imaging (MRSI) of the human prostate at 4.0T using a transmit/receive endorectal coil and a pulse sequence designed specifically for this application. Materials and Methods A solid, reusable endorectal probe was designed for both radiofrequency transmission and reception. Finite difference time domain (FDTD) simulations were performed to characterize the coil's electric field distribution, and temperature measurements were performed in a beef tissue phantom to determine the coil's safe operating limit. The localization by selective adiabatic refocusing (LASER) pulse sequence was implemented using six gradient modulated offset independent adiabatic (GOIA) pulses for very sharp, B1 -insensitive voxel localization. Results Based on the simulations and temperature measurements, the coil's safe operating limit was conservatively estimated to be 1.0W for 15 minutes. The transition width of the GOIA pulse selection profiles was only 6% of the bandwidth, compared with 22% for a specific absorption rate (SAR)-matched conventional adiabatic pulse. Using the coil and pulse sequence described here, MRSI data were successfully acquired from a patient with biopsy-proven prostate cancer, with a nominal voxel size of 0.34 cc in a scan time of 15 minutes. Conclusion This work demonstrates the safe and effective use of a transmit/receive endorectal coil for in vivo MRSI of the prostate. J. Magn. Reson. Imaging 2009;30:335,343. © 2009 Wiley-Liss, Inc. [source] A novel bandpass filter based on complementary split rings resonators and substrate integrated waveguideMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2008Wenquan Che Abstract One novel bandpass filter implemented with combination of two different structures-complementary split rings resonators (CSRRs) and substrate integrated waveguide (SIW) is proposed in this article. Several CSRRs are etched on the surface of SIW to form the stopband with very sharp rejection. One prototype was fabricated, the measured results indicate 30% passband (at ,15 dB return loss), the rejection band ranges from 6.4 GHz to 7.8 GHz, about 20% bandwidth at ,20 dB rejection, the maximum rejection even reaches 50 dB. The rejection skirt is very sharp, only 18 MHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 699,701, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23182 [source] The evolution of the galaxy red sequence in simulated clusters and groupsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008A. D. Romeo ABSTRACT N -body/hydrodynamical simulations of the formation and evolution of galaxy groups and clusters in a , cold dark matter (,CDM) cosmology are used in order to follow the building-up of the colour,magnitude relation in two clusters and in 12 groups. We have found that galaxies, starting from the more massive, move to the red sequence (RS) as they get aged over times and eventually set upon a ,dead sequence' (DS) once they have stopped their bulk star formation activity. Fainter galaxies keep having significant star formation out to very recent epochs and lie broader around the RS. Environment plays a role as galaxies in groups and cluster outskirts hold star formation activity longer than the central cluster regions. However, galaxies experiencing infall from the outskirts to the central parts keep star formation on until they settle on to the DS of the core galaxies. Merging contributes to mass assembly until z, 1, after which major events only involve the brightest cluster galaxies. The emerging scenario is that the evolution of the colour,magnitude properties of galaxies within the hierarchical framework is mainly driven by star formation activity during dark matter haloes assembly. Galaxies progressively quenching their star formation settle to a very sharp ,red and dead' sequence, which turns out to be universal, its slope and scatter being almost independent of the redshift (since at least z, 1.5) and environment. Differently from the DS, the operatively defined RS evolves more evidently with z, the epoch when it changes its slope being closely corresponding to that at which the passive galaxies population takes over the star-forming one: this goes from z, 1 in clusters down to 0.4 in normal groups. [source] Small scale mixing processes at the top of a marine stratocumulus,a case studyTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 622 2007Krzysztof E. Haman Abstract A layer of intensive mixing (entrainment interface layer, [EIL]) at the top of marine stratocumulus under a strong inversion has been investigated with 10 cm resolution using an ultrafast thermometer (UFT-F; temperature), a particle volume monitor PVM,100A (liquid water content), and a fast forward scattering spectrometer probe (FFSSP; droplet spectra). Measurements were collected on board the NCAR C-130 aircraft during research flight RF05 of DYCOMS-II field study. The EIL consists of mutual filaments of cloudy and clear air at different stages of stirring, mixing, and homogenization. Borders between these filaments are often very sharp, with the 10 cm resolution of the instruments being insufficient to characterize them properly in many cases. Certain classifications of these filaments and hypotheses about the mechanisms of their formation have been proposed. The common occurrence of filaments of sizes smaller than the resolution of instruments has been indirectly confirmed. This is in agreement with the observed cloud droplet spectra showing variations of droplet number concentration without significant change of the mean droplet diameter and spectrum width. Copyright © 2007 Royal Meteorological Society [source] Integrated technologies for archaeological investigation; the Celone Valley projectARCHAEOLOGICAL PROSPECTION, Issue 3 2007Marcello Ciminale Abstract A non-intrusive investigation integrating complementary technologies was carried out at four vast archaeological settlements located in the northern part of Apulia (Southern Italy). An aerial photographic survey combined with a high-resolution magnetic investigation was used to detect many buried archaeological features. After processing, both crop marks and magnetic anomalies appeared very sharp and well-defined, outlining the shape and plan of the buried structures with notable accuracy. Furthermore, differential global positioning system measurements were carried out in order to geocode the magnetic grids, to orthorectify the oblique coloured photographs and to make these data sets suitable for input into a GIS; a very good spatial correlation and a more rigorous and comprehensive interpretation of the various data elements were attained. Finally, as a result of this combined and accurate multilayer analysis, an archaeological interpretation was proposed, enabling useful information to be obtained on the transformations that have occurred over time at these study sites. Copyright © 2007 John Wiley & Sons, Ltd. [source] |