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101.
Xu C Miranda-Nieves D Ankrum JA Matthiesen ME Phillips JA Roes I Wojtkiewicz GR Juneja V Kultima JR Zhao W Vemula PK Lin CP Nahrendorf M Karp JM 《Nano letters》2012,12(8):4131-4139
Monitoring the location, distribution and long-term engraftment of administered cells is critical for demonstrating the success of a cell therapy. Among available imaging-based cell tracking tools, magnetic resonance imaging (MRI) is advantageous due to its noninvasiveness, deep penetration, and high spatial resolution. While tracking cells in preclinical models via internalized MRI contrast agents (iron oxide nanoparticles, IO-NPs) is a widely used method, IO-NPs suffer from low iron content per particle, low uptake in nonphagocytotic cell types (e.g., mesenchymal stem cells, MSCs), weak negative contrast, and decreased MRI signal due to cell proliferation and cellular exocytosis. Herein, we demonstrate that internalization of IO-NP (10 nm) loaded biodegradable poly(lactide-co-glycolide) microparticles (IO/PLGA-MPs, 0.4-3 μm) in MSCs enhances MR parameters such as the r(2) relaxivity (5-fold), residence time inside the cells (3-fold) and R(2) signal (2-fold) compared to IO-NPs alone. Intriguingly, in vitro and in vivo experiments demonstrate that internalization of IO/PLGA-MPs in MSCs does not compromise inherent cell properties such as viability, proliferation, migration and their ability to home to sites of inflammation. 相似文献
102.
Wise Erica H.; Sturm Cynthia A.; Nutt Roberta L.; Rodolfa Emil; Schaffer Jack B.; Webb Carol 《Canadian Metallurgical Quarterly》2010,41(4):288
As a profession we are committed to maintaining and enhancing our competence as psychologists in order to most effectively serve the public throughout our careers. While this is a widely shared commitment among psychologists, there is considerably less consensus regarding how best to accomplish this goal. This dilemma is examined from the ethical, educational and legal perspectives. The American Psychological Association (APA) Ethics Code clearly articulates that competence is an ethical duty, although there is little guidance provided in the code as to how to meet this standard. As a profession we have tended to focus on the construct of life-long learning and we have incorporated this principle into our education and training standards. In fact, APA accreditation requires that doctoral programs inculcate this value into our foundational training. The majority of Psychology Licensing Boards have addressed this issue through the endorsement of mandatory continuing education requirements that primarily focus on hours and the content or structure of approved programs. Potential limitations to our ability to effectively self-assess our professional training needs are discussed and several innovative models are presented for integrating effective self-assessment and continuing education. Three invited experts provide commentaries that further explore the challenges and dilemmas posed by the ethical, legal and professional duty to maintain and enhance competence throughout our professional careers. These commentaries broaden the considerations, provide practical suggestions from other professions and provide a vision for the future. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
103.
104.
Abstract The concept of the Rayleigh range, well known in the theory of coherent beams, is generalized to a class of partially coherent beams. Curves are presented which show the dependence of the Rayleigh range on the spot size of the beam and on the spectral degree of coherence of the light in the plane of the waist. 相似文献
105.
Abstract The spectral properties and the coherence properties of Gaussian Schell-model beams, propagating in dispersive and absorbing media, are discussed. Unlike in free space, the ratio of the transverse spectral correlation length to the beam width is found to increase on propagation. Consequently upon propagation the beam becomes spatially more coherent at each frequency. Numerical results for the spectrum and for the degrees of spectral and of temporal coherence of the field are presented for some selected values of the beam parameters and for several values of the propagation distance. Propagation in a gain medium is also briefly discussed. 相似文献
106.
A detailed analysis of microchannel/microgap heat transfer data for two-phase flow of refrigerants and dielectric liquids, gathered from the open literature and sorted by the Taitel and Dukler flow regime mapping methodology, is performed. Annular flow is found to be the dominant regime for this thermal transport configuration and to grow in importance with decreasing channel diameter. A characteristic M-shaped heat transfer coefficient variation with quality (or superficial velocity) for the flow of refrigerants and dielectric liquids in miniature channels is identified. The inflection points in this M-shaped curve are seen to equate approximately with flow regime transitions, including a first maximum at the transition from Bubble to Intermittent flow and a second maximum at moderate qualities in Annular flow, just before local dryout begins. The predictive accuracy of five classical two-phase heat transfer correlations for miniature channel flow is examined. Selecting the best fitting of the classical correlations for each of the flow regime categories is seen to yield predictive agreement with regime-sorted heat transfer coefficients that does not depart significantly from the agreement found in large pipes and channels. 相似文献
107.
De Brabandere H Forsgard N Israelsson L Petterson J Rydin E Waldebäck M Sjöberg PJ 《Analytical chemistry》2008,80(17):6689-6697
The structures of organic phosphorous (P) compounds in aquatic sediments are to a large extent unknown although these compounds are considered to play an important role in regulating lake trophic status. To enhance identification of these compounds, a liquid chromatography (LC) method for their separation was developed. The stationary phase was porous graphitic carbon (PGC), and the mobile phases used in the gradient elution were compatible with both inductive coupled plasma atomic emission spectroscopy (ICP-AES) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). With LC-ICP-AES, eight different P containing peaks could be observed in the P chromatogram indicating that at least eight different P compounds were separated. With the setup of an information dependent acquisition (IDA) with ESI-MS/MS, the mass over charge ( m/ z) of compounds containing a phosphate group (H 2PO 3 (-), m/ z 97) could be measured and further fragmentation experiments gave additional information on the structure of almost 40 separated P compounds, several were verified to be nucleotides. ICP-AES was very suitable in the development of the LC method and allowed screening and quantification of P compounds. The presented LC-ESI-MS/MS technique was able to identify several sediment organic P compounds. 相似文献
108.
Bieschke Kathleen J.; Bell Debora; Davis Claytie III; Hatcher Robert; Peterson Roger; Rodolfa Emil R. 《Canadian Metallurgical Quarterly》2011,5(3):123
We are frustrated with the internship imbalance. Twenty years ago, those of us involved in academic training programs prepared students in our doctoral programs for the internship application process by meeting with them for an hour and giving them a few pointers. Now, the focus on securing an internship seems to pervade all aspects of doctoral education. We listen to students worry that they don’t have sufficient hours, assessment experience, or diverse practicum placements. As the Association of Psychology Postdoctoral and Internship Centers (APPIC) Match approaches, we meet with students more frequently, helping them to prepare their applications and carefully construct their list of internship sites. We devote time helping students to complete the APPIC Application for Psychology Internship (AAPI), prepare for interviews, and rank sites. Those of us who are involved in internship training programs spend extensive hours reviewing hundreds of applications in Phase I and Phase II of the APPIC Match. We respond to applicant concerns, questions, and anxiety. And all of us try to provide support and consolation, as well as some understanding about “what went wrong” to those students who aren’t matched. When we have a moment, we look beyond the students in front of us and worry about the future of our profession. How is it possible that we’ve gotten ourselves into this mess? Hatcher’s (this issue, pp. 126 –140) article (a manifesto, if you will) has the potential to point us in a new direction. Our hope is that each of you, like us, will view Hatcher’s article as the beginning of a paradigm shift in terms of how we characterize this problem and its potential solutions. His innovative and bold view of how the professional training community can work collaboratively to reorganize has the potential to effectively impact the internship imbalance and the quality of the profession as a whole. By likening the internship imbalance to a resource management issue similar to what has been encountered in regard to other resources such as crops and forests, Hatcher provides us with an opportunity to rise above our own positions to draw upon existing, evidence-based approaches to cooperative solutions that can benefit all involved. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
109.
Han X Bian J Eaker DR Kline TL Sidky EY Ritman EL Pan X 《IEEE transactions on medical imaging》2011,30(3):606-620
Micro-computed tomography (micro-CT) is an important tool in biomedical research and preclinical applications that can provide visual inspection of and quantitative information about imaged small animals and biological samples such as vasculature specimens. Currently, micro-CT imaging uses projection data acquired at a large number (300-1000) of views, which can limit system throughput and potentially degrade image quality due to radiation-induced deformation or damage to the small animal or specimen. In this work, we have investigated low-dose micro-CT and its application to specimen imaging from substantially reduced projection data by using a recently developed algorithm, referred to as the adaptive-steepest-descent-projection-onto-convex-sets (ASD-POCS) algorithm, which reconstructs an image through minimizing the image total-variation and enforcing data constraints. To validate and evaluate the performance of the ASD-POCS algorithm, we carried out quantitative evaluation studies in a number of tasks of practical interest in imaging of specimens of real animal organs. The results show that the ASD-POCS algorithm can yield images with quality comparable to that obtained with existing algorithms, while using one-sixth to one quarter of the 361-view data currently used in typical micro-CT specimen imaging. 相似文献
110.
Jiří Vondráček Emil PelikánOndřej Konár Jana ČermákováKryštof Eben Marek MalýMarek Brabec 《Applied Energy》2008
In this paper we present a statistical approach to natural gas consumption estimation of individual residential and small commercial customers. The approach is based on nonlinear regression principles. Parameters are estimated using mainly two real data sets – ordinary (approximately annual) meter readings of almost all customers and additional (approximately monthly) meter readings designed and operated within the frame of cooperation between the Institute of Computer Science of the Czech Academy of Sciences (ICS) and the West Bohemian Gas Distribution Company, a part of the RWE Group (WBG). The model was tested on various data sets. It has broad applicability in many areas of gas industry. 相似文献