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排序方式: 共有326条查询结果,搜索用时 15 毫秒
1.
Review of book: Media violence and its effects on aggression: Assessing the scientific evidence, by Jonathan L. Freedman. Toronto: ON: University of Toronto Press, 2002, 227 pp. Hardcover. ISBN 0-8020-3553-1. Reviewed by Claire Crooks. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
Investigated stress and well-being in adolescence to examine the ability of exercise to buffer stress-induced deteriorations in physical health. 384 female 7th–8th graders completed a life events survey, the Seriousness of Illness Rating Scale, and an activity questionnaire at the beginning and end of the academic year. Analyses revealed that the negative impact of stressful life events on health declined as exercise levels increased. Findings suggest that exercise may be a valuable resource for combating life stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
Deconvolution methods for mitigation of transverse blurring in optical coherence tomography. 总被引:3,自引:0,他引:3
Tyler S Ralston Daniel L Marks Farzad Kamalabadi Stephen A Boppart 《IEEE transactions on image processing》2005,14(9):1254-1264
Imaging resolution in optical coherence tomography (OCT) is a key determinant for acquiring clinically useful optical biopsies of tissues. In contrast to light or confocal microscopy, the axial and transverse resolutions in OCT are independent and each can be analyzed individually. A method for mitigating transverse blurring and the apparent loss of transverse resolution in OCT by means of Gaussian beam deconvolution is presented. Such a method provides better representation of a specimen by using known physical parameters of a lens. To implement this method, deconvolution algorithms based on a focal-dependent kernel are investigated. First, the direct inverse problem is investigated using two types of regularization, truncated singular value decomposition, and Tikhonov. Second, an iterative expectation maximization algorithm, the Richardson-Lucy algorithm, with a beam-width-dependent iteration scheme is developed. A dynamically iterative Richardson-Lucy algorithm can reduce transverse blurring by providing an improvement in the transverse point-spread-function for sparse scattering samples in regions up to two times larger than the confocal region of the lens. These deblurring improvements inside and outside of the confocal region, which are validated experimentally, are possible without introducing new optical imaging hardware or acquiring multiple images of the same specimen. Implementation of this method in sparse scattering specimens, such as engineered tissues, has the potential to improve cellular detection and categorization. 相似文献
4.
The eighth sentences shpuld read as follows. rFosLZGSTweakly associates beyond a dimer (Ka 4x104 M1)and rJunLZGST associates indefinitely (Ka 4x105M1), consistent with an isodesmic model of association. 相似文献
5.
Jonathon S. Hare Sina Samangooei Paul H. Lewis 《Multimedia Tools and Applications》2014,71(3):1215-1248
The ability to handle very large amounts of image data is important for image analysis, indexing and retrieval applications. Sadly, in the literature, scalability aspects are often ignored or glanced over, especially with respect to the intricacies of actual implementation details. In this paper we present a case-study showing how a standard bag-of-visual-words image indexing pipeline can be scaled across a distributed cluster of machines. In order to achieve scalability, we investigate the optimal combination of hybridisations of the MapReduce distributed computational framework which allows the components of the analysis and indexing pipeline to be effectively mapped and run on modern server hardware. We then demonstrate the scalability of the approach practically with a set of image analysis and indexing tools built on top of the Apache Hadoop MapReduce framework. The tools used for our experiments are freely available as open-source software, and the paper fully describes the nuances of their implementation. 相似文献
6.
Previous studies with macrophages that had been prelabeled with [14C]arachidonic acid (20∶4) have shown that condensed tannin is a potent agonist for the release of arachidonic acid. However,
it has not been demonstrated that the percentage release of [14C]20∶4 accurately reflects the metabolic activity of the endogenous 20∶4 pool. In order to measure the 20∶4 mass release relative
to the total cellular 20∶4 pool, the free fatty acids of freshly isolated alveolar macrophages were derivatized with a fluorescent
reagent, and then separated and quantified by high-performance liquid chromatography. The amounts of esterified fatty acids
were measured by gas chromatography of the methyl esters. Free fatty acid levels were compared to those of the total esterified
plus unesterified fatty acids to determine the actual percentage released of each fatty acid. Tannin-stimulated release of
20∶4 mass reflected that previously reported for the release of [14C]20∶4 label but at a slower rate and at a much lower percentage indicating that [14C]20∶4 had been incorporated into part of a more reactive pool. The specificity of the fatty acid release induced by tannin
and β-1,3-glucan, a known agonist for 20∶4 release, was also examined. Both agonists promoted an increase in the levels of
free 20∶4 and of other fatty acids. A comparison of the absolute increases of each of the fatty acids indicated that tannin
caused a preferential increase in the mass of free 20∶4, whereas β-1,3-glucan evoked a selective increase in the mass of 16∶0.
Deceased. 相似文献
7.
Multimer formation as a consequence of separate homodimerization domains: the human c-Jun leucine zipper is a transplantable dimerization module 总被引:1,自引:0,他引:1
Riley L.G.; Ralston G.B.; Weiss A.S. 《Protein engineering, design & selection : PEDS》1996,9(2):223-230
Human c-Jun and c-Fos leucine zipper domains were examined fortheir ability to serve as autonomous dimerization domains aspart of a heterologous protein construct. Schistosoma japonicumglutathione S-transferase (GST) was fused to recombinant Junleucine zipper (rJunLZ) and Fos leucine zipper (rFosLZ) domains.SDSPAGE snapshot analyses based on disulphidelinkage of monomers demonstrated the ability of rJunLZ to functionas a dimerization motif in a foreign protein environment. Sterichindrance prevented formation of rJunLZGST::rFosLZGSTheterodimers whereas rJunLZGST::rFosLZ and rJunLZ::rFosLZGSTformed readily. Furthermore, rJunLZGST generated homodimerssuggesting fusion protein heterodimers interact differentlyto homodimers. Gel filtration chromatography confirmed thatGST is a dimer in solution and that attachment of a leucinezipper domain allows further interactions to take place. Sedimentationequilibrium analyses showed that GST is a stable dimer (Ka >106 M-1) with no higher multimeric forms. rFosLZGST weaklyassociates beyond a dimer (Ka {small tilde}4x105 M-1) and rJunLZGSTassociates indefinitely (Ka {small tilde}4x106 M-1), consistentwith an isodesmic model of association. The interaction of theseleucine zippers independently of GST association demonstratestheir utility in the modification of proteins when multimerformation is desired. 相似文献
8.
Yooyoung Lee James J. Filliben Ross J. Micheals P. Jonathon Phillips 《Computer Vision and Image Understanding》2013,117(5):532-550
The purpose of this paper is to introduce an effective and structured methodology for carrying out a biometric system sensitivity analysis. The goal of sensitivity analysis is to provide the researcher/developer with insight and understanding of the key factors—algorithmic, subject-based, procedural, image quality, environmental, among others—that affect the matching performance of the biometric system under study. This proposed methodology consists of two steps: (1) the design and execution of orthogonal fractional factorial experiment designs which allow the scientist to efficiently investigate the effect of a large number of factors—and interactions—simultaneously, and (2) the use of a select set of statistical data analysis graphical procedures which are fine-tuned to unambiguously highlight important factors, important interactions, and locally-optimal settings. We illustrate this methodology by application to a study of VASIR (Video-based Automated System for Iris Recognition)—NIST iris-based biometric system. In particular, we investigated k = 8 algorithmic factors from the VASIR system by constructing a (26?1 × 31 × 41) orthogonal fractional factorial design, generating the corresponding performance data, and applying an appropriate set of analysis graphics to determine the relative importance of the eight factors, the relative importance of the 28 two-term interactions, and the local best settings of the eight algorithms. The results showed that VASIR’s performance was primarily driven by six factors out of the eight, along with four two-term interactions. A virtue of our two-step methodology is that it is systematic and general, and hence may be applied with equal rigor and effectiveness to other biometric systems, such as fingerprints, face, voice, and DNA. 相似文献
9.
Azam Khalili Mohammad Ali Tinati Amir Rastegarnia Jonathon A. Chambers 《International Journal of Adaptive Control and Signal Processing》2012,26(2):171-180
In this paper, we study the effect of noisy channels on the transient performance of diffusion adaptive network with least‐mean squares (LMS) learning rule. We first drive the update equation of diffusion LMS which incorporates the effects of noisy channels. Then, using the framework of fundamental weighted energy conservation relation, we derive closed‐form expressions for learning curves in terms of mean‐square deviation and excess mean‐square error. We also find the mean and mean‐square stability bounds of step‐size for diffusion LMS with noisy channels. We show that although noisy channels affect the performance of the diffusion LMS network, the stability bounds of the step‐size are the same form as in the ideal channels case. The derived closed‐form expressions are shown to provide a good match with values found by simulation. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
10.
Development and Validation of an Artificial Mechanical Skin Model for the Study of Interactions between Skin and Microneedles 下载免费PDF全文
Sahan A. Ranamukhaarachchi Thomas Schneider Sarah Lehnert Lisa Sprenger Jonathon R. Campbell Iman Mansoor Jacqueline C. Y. Lai Kimit Rai Jan Dutz Urs O. Häfeli Boris Stoeber 《大分子材料与工程》2016,301(3):306-314
Microneedles are small needle‐like structures that are almost invisible to the naked eye. They have an immense potential to serve as a valuable tool in many medical applications, such as painless vaccination. Microneedles work by breaking through the stratum corneum, the outermost barrier layer of the skin, and providing a direct path for drug delivery into the skin. A lot of research has been presented over the past two decades on the applications of microneedles, yet the fundamental mechanism of how they interact, pressure, and penetrate the skin in its native state is worth examining further. As such, a major difficulty with understanding the mechanism of microneedle–skin interaction is the lack of an artificial mechanical human skin model to use as a standardized substrate. In this research news, the development of an artificial mechanical skin model based on a thorough mechanical study of fresh human and porcine skin samples is presented. The artificial mechanical skin model can be used to study the mechanical interactions between microneedles and skin, but not diffusion of molecules across skin. This model can assist in improving the performance of microneedles by enhancing the reproducibility of microneedle depth insertions for optimal drug delivery and biosensing.