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排序方式: 共有88条查询结果,搜索用时 31 毫秒
1.
JN Yu FH Fahey HD Gage CG Eades BA Harkness CA Pelizzari JW Keyes 《Canadian Metallurgical Quarterly》1995,36(12):2333-2338
The purpose of this study was to develop an accurate, retrospectively applicable procedure for registering thoracic studies from different modalities in a short amount of time and with minimal operator intervention. METHODS: CT and PET studies were acquired from six patients. The pleural surfaces in both image sets were determined by segmenting based on 50% of the maximum soft-tissue value in the study. These surfaces were converted into three-dimensional volumes and used to register the CT and PET studies in three dimensions using a sum of least squares fitting approach. The registered PET study was then displayed in a hot metal scale overlayed on top of the gray scale CT study. The accuracy of the fit was evaluated through a phantom study and preliminary clinical evaluation. RESULTS: A phantom study was performed to determine the limits of this technique. The accuracy was determined to be less than 2.3 mm in the x and y direction and 3 mm in the z direction. Preliminary clinical evaluation was also performed with encouraging results. CONCLUSION: This technique accurately registers PET and CT images of the thorax, retrospectively, without the need for external fiducial markers or other a priori action. 相似文献
2.
Fabrication and Optical Properties of Periodic Ag Nano‐Pore and Nano‐Particle Arrays with Controlled Shape and Size over Macroscopic Length Scales 下载免费PDF全文
Colm T. Mallon Kiang W. Kho Houda Gartite Robert J. Forster Tia E. Keyes 《Advanced Engineering Materials》2018,20(1)
A facile and economical route to preparation of highly ordered sliver pore or particle arrays with controlled pore‐shape and size extended over cm2 areas is described. The substrates are prepared at planar and curved surfaces via sphere‐imprinted polymer (PDMS) templating using polystyrene spheres with diameters of 820, 600, or 430 nm. Nano‐pore arrays are created by sputtering 80 nm of Ag directly onto the templates and nano‐particle arrays are prepared by electrode‐less deposition of Ag from Tollen's reagent. The shape of the nano‐pore or particles in the array conformed to that of the imprint of the sphere on the template. Stretching the flexible template enable creation of cuboid shaped nano‐voids and nano‐particles following Ag deposition. Diffuse reflectance from the spherical Ag nano‐cavity arrays showed absorbance maxima at wavelengths comparable similar to the diameter of the templating sphere, whereas reflectance from the cuboid arrays, showed little correlation with the sphere diameter. The cuboid nano‐particle arrays showed the most intense visible absorption which is red‐shifted compared to the spherical arrays. White light diffraction from the arrays, observed by rotating 1 cm2 substrates relative to a fixed light source, reflected exactly the symmetry axes of the periodic nano‐features in the arrays demonstrating the remarkable macroscopic order of the periodic structures. Raman spectra of 1‐benzenethiol adsorbed at the arrays indicated SERS enhancements from the substrates are attributed mainly to surface nano‐roughness with only moderate contributions from the periodically corrugated structures. Despite excitation at the major resonance dip in the reflectance spectrum, a weak, localized rim dipole mode is found to elicit a small increase in the SERS enhancement factor for the 430 nm diameter spherical arrays. FDTD studies of nano‐void arrays provided insights into v arious factors affecting the SERS experiment and confirmed the array's plasmonic spectra are dominated by propagating plasmon modes under microscope excitation/collection angles. 相似文献
3.
S. P. Ahrenkiel M. W. Wanlass J. J. Carapella L. M. Gedvilas B. M. Keyes R. K. Ahrenkiel H. R. Moutinho 《Journal of Electronic Materials》2004,33(3):185-193
Low-bandgap, lattice-mismatched GaxIn1−xAs (GaInAs) grown using InAsyP1−y (InAsP) compositional-step grades on InP is a primary choice for lightabsorbing, active layers in high-efficiency thermophotovoltaic
(TPV) devices. The GaInAs/InAsP double heterostructures (DHs) show exceptional minority carrier lifetimes of up to several
microseconds. We have performed a characterization survey of 0.4–0.6-eV GaInAs/InAsP DHs using a variety of techniques, including
transmission electron microscopy (TEM). Dislocations are rarely observed to thread into the GaInAs active layers from the
InAsP buffer layers that terminate the graded regions. Nearly complete strain relaxation occurs in buried regions of the InAsP
grades. The buffer-layer strain prior to deposition of the active layer is virtually independent of the net misfit. Foreknowledge
of this buffer-layer strain is essential to correctly lattice match the buffer to the GaInAs active layer. 相似文献
4.
To determine whether peptides of the insulin-like growth factor (IGF) system might be useful indicators of nutritional adequacy in premature infants, we studied 50 premature (25-34 weeks gestation) infants prospectively to define the relationship between nutrient intake and serum concentrations of IGF-I, IGF-binding protein-2 (IGFBP-2), and IGFBP-3. Each infant was monitored for at least 2 weeks. Nutrient intake was quantified from daily logs; weight was determined daily, and measurements of IGF-I, IGFBP-2, and IGFBP-3 in serum were made twice weekly. Serum IGF-I correlated strongly with length of gestation, increasing 4.03 +/- 0.95 ng/mL for each additional week of gestation (P < 0.0001) and 0.36 +/- 0.07 ng/mL day each day since birth (P < 0.0001). A higher intake of calories increased IGF-I by 0.07 +/- 0.01 ng/mL for each calorie per kg ingested over the previous 3 days (P < 0.0001). IGF-I increased quadratically as protein intake increased. For each change of 1% in calories as protein squared, IGF-I increased 0.36 +/- 0.11 ng/mL (P < 0.0001). Serum IGFBP-3 concentrations also correlated with length of gestation, increasing 25.06 +/- 11.83 micrograms/L.wk (P = 0.035) and 4.14 +/- 1.33 micrograms/.day since birth (P = 0.003). Unlike IGF-I, variation in the amount of protein supplied did not change IGFBP-3. As calorie intake increased, IGFBP-3 increased by 0.54 +/- 0.17 microgram/L for each calorie per kg consumed over the previous 3 days (P = 0.0015). In contrast to IGF-I and IGFBP-3, IGFBP-2 declined as the length of gestation increased (56.12 +/- 16.92 ng/mL.week; P = 0.001) and with each additional day of life (7.57 +/- 2.44 ng/mL.day; P = 0.003). Dietary protein, the predominant regulator of IGFBP-2, caused a decrease of 33.22 +/- 9.00 ng/mL with each percent increase in dietary calories as protein (P < 0.0003). Calorie intake had less effect on IGFBP-2 than protein intake. These results indicate that each of the three peptides studied is regulated in premature infants by nutritional intake, and that their regulatory patterns are qualitatively similar to those observed in older individuals. Measurements of these peptides in premature infants may be useful indicators of nutritional status and adequacy of nutrient intake. 相似文献
5.
6.
Richard Le Heron Glen W. Atkinson Henry Teune Greg Mason Henk Voogd Brenda J. Moscove Patricia Gober Thomas A. Reiner Richard F. Curtis Stephen F. Seninger W. W. Hall Jr. John E. Keith M. Van Naelten R. W. Keyes John Huttman Robert B. Weeden Clarence G. Ray Steven E. Daniels F. Larry Leistritz Patrizia Spinetti Peter D. Beaulieu F. J. Potgieter David L. Barkley Charles A. Berry Jean E. Weber Wieslaw Rozlucki Jesse Burkhead John R. Ottensmann Noel D. Uri Erlet Cater J. Barry Riddell Ernesto Quintanilla John F. McDonald Jon R. Miller Stan Czamanski 《The Annals of Regional Science》1986,20(1):87-144
7.
PP Dendy JW McNab AF MacDonald WI Keyes JM Carrill 《Canadian Metallurgical Quarterly》1977,50(596):555-561
The Aberdeen section scanner provides, in addition to conventional views, a display of the distribution of radioactivity in a tomographic section of the brain. This paper examined the value of this additional information. Scans of lesions confirmed pathologically or radiologically, along with normal and doubtful cases, were examined after a careful randomization procedure. During the course of the study each set of conventional views was examined twice, once without and once with a tomographic section view. In two out of 29 cases (7%) the lesion was diagnosed only with the aid of the tomographic section scan. Improved accuracy of diagnosis with the tomographic section view was significant at the 1% level or better. 相似文献
8.
A. N. Spector Lay James Gibson Ashok K. Dutt William F. Hyde Paul B. Sherman Hans-Jurg Buttler Bernard Malamud Robert N. Anderson M. Penouil R. W. Keyes Lee R. McPheters William R. Eadington Kurt Puchinger Arthur E. Kartman Charles E. Starnes J. Barry Riddell Erick Sheppard Leon E. Zonn Craig Moore Neil S. Grigg K. Shimizu Daniel A. Griffith Noel D. Uri Micheal Ross Jack E. Adams Robert G. Fletcher Karol J. Krotki Peter D. Beaulieu Fred E. Case W. Edwin Derrick Barry D. Solomon Debnath Mookherjee John E. Keith Yuk Lee Andrew A. Dzurik W. W. Hall Jr. Lloyd W. Klemke Ted J. Adamczyk 《The Annals of Regional Science》1981,15(3):82-146
9.
Luc Berger‐Vergiat Haim Waisman Badri Hiriyur Ray Tuminaro David Keyes 《International journal for numerical methods in engineering》2012,90(3):311-328
Traditional algebraic multigrid (AMG) preconditioners are not well suited for crack problems modeled by extended finite element methods (XFEM). This is mainly because of the unique XFEM formulations, which embed discontinuous fields in the linear system by addition of special degrees of freedom. These degrees of freedom are not properly handled by the AMG coarsening process and lead to slow convergence. In this paper, we proposed a simple domain decomposition approach that retains the AMG advantages on well‐behaved domains by avoiding the coarsening of enriched degrees of freedom. The idea was to employ a multiplicative Schwarz preconditioner where the physical domain was partitioned into “healthy” (or unfractured) and “cracked” subdomains. First, the “healthy” subdomain containing only standard degrees of freedom, was solved approximately by one AMG V‐cycle, followed by concurrent direct solves of “cracked” subdomains. This strategy alleviated the need to redesign special AMG coarsening strategies that can handle XFEM discretizations. Numerical examples on various crack problems clearly illustrated the superior performance of this approach over a brute force AMG preconditioner applied to the linear system. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
10.
Most psychiatrists enter into a variety of professional relationships with other clinicians in which they prescribe medications or make recommendations about pharmacotherapy. This paper describes a set of guidelines for prescribing psychiatrists involved in consultation, collaboration, and supervision with other clinicians. The guidelines were developed by psychiatrists for the Harvard Risk Management Foundation. The terms consultation, collaboration, and supervision are defined, and the psychiatrist's roles and responsibilities in each type of arrangement are described. The guidelines limit consultation and collaboration to relationships with professionals who are licensed or credentialed. Based on the definitions, the paper describes a structure for working with other clinicians, which begins with a thorough assessment of the context and circumstances of the clinical situation. The guidelines strongly encourage structured communication among clinicians and with the patient and significant others, as well as clarification by clinicians of their respective responsibilities for treatment and follow-up. 相似文献