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排序方式: 共有113条查询结果,搜索用时 234 毫秒
1.
In eukaryotes, microRNAs (miRNAs) have roles in development, homeostasis, disease and the immune response. Recent work has shown that plant and mammalian miRNAs also mediate cross-kingdom and cross-domain communications. However, these studies remain controversial and are lacking critical mechanistic explanations. Bacteria do not produce miRNAs themselves, and therefore it is unclear how these eukaryotic RNA molecules could function in the bacterial recipient. In this review, we compare and contrast the biogenesis and functions of regulatory RNAs in eukaryotes and bacteria. As a result, we discovered several conserved features and homologous components in these distinct pathways. These findings enabled us to propose novel mechanisms to explain how eukaryotic miRNAs could function in bacteria. Further understanding in this area is necessary to validate the findings of existing studies and could facilitate the use of miRNAs as novel tools for the directed remodelling of the human microbiota.  相似文献   
2.
The effect on mechanical behavior of ZrO2 additions to a dental porcelain was investigated. The ZrO2 was introduced into the glassy matrix phase of the porcelain by refritting the all-glass porcelain constituent. X-ray diffraction indicated that a sizeable fraction of the ZrO2 was retained in the tetragonal form after the porcelain was fired. Zirconia additions to the porcelain produced substantial improvements in fracture toughness, strength, and thermal shock resistance.  相似文献   
3.
Choice between a variable and a fixed food source was studied in pigeons. The variable source yielded different durations of access to food (changed across experimental conditions) uniquely associated with equiprobable delays of either 20 sec or 60 sec, timed from the choice point. A comparison, elapsing alternative (time-left procedure [J. Gibbon and R. M. Church; see PA, Vol 67:2812]), was associated with fixed access to feeder after a 60-sec delay, timed from the beginning of the trial. Preference was best characterized as reflecting an average of the 2 local rates of reinforcement in the variable alternative (the average of the ratio of each standard amount and its associated delay). The averaging rule characterized initial choice link data well, but terminal link responding showed that Ss also remembered the 2 delay–amount combinations separately. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
4.
Perceptual analysis of handwritten signatures for biometric authentication   总被引:1,自引:0,他引:1  
The Internet has stimulated increased activity to address key problems relating to the implementation of reliable and robust biometric identity checking. Although not always the biometric modality most readily adopted in such an environment, the handwritten signature continues to offer many advantages over some other more commonly considered biometrics. The authors address some key issues relating to the nature of the handwritten signature and, especially, the strategies used by humans in analysing signature data. Through experimental studies and an analytical investigation, the paper identifies characteristics of the signature which influence its resilience to fraudulent penetration, pointing to some important principles on which to build procedures for both automated and non-automated identity authentication.  相似文献   
5.
In this paper, we present a novel and robust road tracking system for vision-based personal navigation. Novelty of the work includes the use of multiple Condensation filters to track the road of arbitrary shape and automatic switching between trackers according to road conditions. The approach allows the road to be represented as a simple hyperbola. It also supports the representation of the road as a sequence of connected arcs/segments so that information from a digital map can be integrated into tracking. The parameters of the hyperbola road model are estimated using multiple vanishing points located in image strips. The road tracking method is robust in dealing with complex road shapes, background clutters, shadows, and road markings. Experiments using real videos demonstrate the robustness of our approach.  相似文献   
6.
Visuo-spatial neglect (VSN) is a post-stroke condition in which a patient fails to respond to stimuli on one side of the visual field. Using an established pencil-and-paper-based method for the assessment of VSN (the Rivermead Behavioural Inattention Test) as a reference, a battery of computer-based hand-drawing tests is developed and shown to be effective in distinguishing between stroke subjects with and without neglect. The novel approach adopts measurements both of the outcome and the process by which the drawing tasks are executed. This approach provides a novel diagnostic capability which results in increased test sensitivity, a more objective assessment and a reduction in overall evaluation time. The paper describes the development of a binary assessment system using the computer-based acquisition and analysis of task data alongside feature selection techniques to maximise performance.
R. M. GuestEmail:
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7.
Abstract. A new parallel hybrid decision fusion methodology is proposed. It is demonstrated that existing parallel multiple expert decision combination approaches can be divided into two broad categories based on the implicit decision emphasis implemented. The first category consists of methods implementing computationally intensive decision frameworks incorporating a priori information about the target task domain and the reliability of the participating experts, while the second category encompasses approaches implementing group consensus without assigning any importance to the reliability of the experts and ignoring other contextual information. The methodology proposed in this paper is a hybridisation of these two approaches and has shown significant performance enhancements in terms of higher overall recognition rates along with lower substitution rates. Detailed analysis using two different databases supports this claim. Received January 19, 1999 / Revised March 20, 2000  相似文献   
8.
The provision of countryside recreation facilities at a local level is likely to receive increasing attention during the next decade. As an integral part of the assessment of the quality of present provision within the Congleton District of Cheshire (U.K.) five site surveys were made. Each site provides different facilities for recreation and interview questions were designed to investigate the background of the visitors and the nature of the interplay between site and visitor. The analysis of answers attempts to illustrate those aspects of this interrelationship, which may be important during the consideration of future provision of recreation sites and their management.  相似文献   
9.
Responsiveness is a critical metric for web performance. Recent work in the Internet Engineering Task Force (IETF) and World Wide Web Consortium (W3C) has resulted in a new set of web protocols, including definition of the hypertext transfer protocol version 2 (HTTP/2) and a corresponding set of TCP updates. Together, these have been designed to reduce the web page download latency compared with HTTP/1.1. This paper describes the main features of the new protocols and discusses the impact of path delay on their expected performance. It then presents a set of tests to evaluate whether current implementations of the new protocols can offer benefit with an operational satellite access network and suggests how the specifications can evolve and be tuned to further enhance performance for long network paths. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
10.
The provision of countryside recreation facilities at a local level is likely to receive increasing attention during the next decade. As an integral part of the assessment of the quality of present provision within the Congleton District of Cheshire (U.K.) five site surveys were made. Each site provides different facilities for recreation and interview questions were designed to investigate the background of the visitors and the nature of the interplay between site and visitor. The analysis of answers attempts to illustrate those aspects of this interrelationship which may be important during the consideration of future provision of recreation sites and their management.  相似文献   
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