检索结果-内蒙古大学图书馆

Efficient adaptive, algorithms and minimax bounds for zero. delay, lossy source coding

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2004年第8期52卷 2337-2347页

作者： György, A Linder, T Lugosi, G Queens Univ Dept Math & Stat Kingston ON K7L 3N6 Canada Pompeu Fabra Univ Dept Econ Barcelona 08005 Spain

Zero-delay lossy source coding schemes are considered for, both individual sequences and random sources. Performance is measured by the distortion redundancy,which is defined as the difference between the normalized cumulative mean squared distortion of the scheme and the normalized cumulative distortion of the best scalar quantizer of the same rate that is matched to the entire sequence to be encoded. By improving and generalizing a scheme of Linder and Lugosi, Weissman and Merhav showed the existence of a randomized scheme that, for any bounded individual sequence of length n, achieves a distortion redundancy 0 (n (-1/3) log n). However, both schemes have prohibitive complexity (both space and time), which makes practical implementation infeasible. In this paper, we present an algorithm that computes Weissman and Merhav's scheme efficiently. In particular, we introduce, an algorithm with encoding complexity 0 (n(4/3)) and distortion redundancy 0(n(-1/3) log n). The complexity can be made linear in the sequence length n at the price of increasing the distortion redundancy to 0(n(-1/4) rootlog n). We also consider the problem of minimax distortion redundancy in zero-delay lossy coding of random sources. By introducing a simplistic scheme and proving a lower bound, we show that for the class of bounded memoryless sources, the minimax expected distortion redundancy is upper and lower bounded by constant multiples of n (-1/2).

关键词： algorithmic efficiency individual sequences lossy source coding minimax redundancy scalar quantization sequential coding

来源：评论

学校读者我要写书评

暂无评论

Efficient Tracking of Large Classes of Experts

引用

IEEE TRANSACTIONS ON INFORMATION THEORY 2012年第11期58卷 6709-6725页

作者： Gyoergy, Andras Linder, Tamas Lugosi, Gabor Hungarian Acad Sci Machine Learning Res Grp Comp & Automat Res Inst H-1111 Budapest Hungary Queens Univ Dept Math & Stat Kingston ON K7L 3N6 Canada Pompeu Fabra Univ Dept Econ Barcelona 08005 Spain Pompeu Fabra Univ ICREA Barcelona 08005 Spain

In the framework of prediction of individual sequences, sequential prediction methods are to be constructed that perform nearly as well as the best expert from a given class. We consider prediction strategies that compete with the class of switching strategies that can segment a given sequence into several blocks, and follow the advice of a different "base" expert in each block. As usual, the performance of the algorithm is measured by the regret defined as the excess loss relative to the best switching strategy selected in hindsight for the particular sequence to be predicted. In this paper, we construct prediction strategies of low computational cost for the case where the set of base experts is large. In particular, we provide a method that can transform any prediction algorithm A that is designed for the base class into a tracking algorithm. The resulting tracking algorithm can take advantage of the prediction performance and potential computational efficiency of A in the sense that it can be implemented with time and space complexity only O(n(gamma) ln n) times larger than that of A, where n is the time horizon and gamma >= 0 is a parameter of the algorithm. With A properly chosen, our algorithm achieves a regret bound of optimal order for gamma > 0 , and only O(ln n) times larger than the optimal order for gamma = 0 for all typical regret bound types we examined. For example, for predicting binary sequences with switching parameters under the logarithmic loss, our method achieves the optimal O(ln n) regret rate with time complexity O(n(1+gamma) ln n) for any gamma is an element of (0, 1).

关键词： Algorithmic efficiency compound experts changing environments data compression individual sequences nonstationary sources sequential coding sequential decision making sequential prediction

来源：评论

学校读者我要写书评

暂无评论

ON THE MINIMUM DESCRIPTION LENGTH PRINCIPLE FOR SOURCES WITH PIECEWISE-CONSTANT PARAMETERS

引用

IEEE TRANSACTIONS ON INFORMATION THEORY 1993年第6期39卷 1962-1967页

作者： MERHAV, N Department of Electrical Engineering Technion-Israel Institute of Technology Haifa Israel

Universal lossless coding in the presence of finitely many abrupt changes in the statistics of the source, at unknown points, is investigated. The minimum description length (MDL) principle is derived for this setting. In particular, it is shown that for any uniquely decipherable code, for almost every combination of statistical parameter vectors governing each segment, and for almost every vector of transition instants, the minimum achievable redundancy is composed from 0.5 log n/n bits for each unknown segmental parameter and log n /n bits for each transition, where n is the length of the input string. This redundancy is shown to be attainable by a strongly sequential universal encoder, i.e., an encoder that does not utilize the knowledge of a prescribed value of n.

关键词： MINIMUM DESCRIPTION LENGTH UNIVERSAL coding sequential coding SEGMENTATION EDGE DETECTION

来源：评论

学校读者我要写书评

暂无评论

sequential Firing Codes for Time in Rodent Medial Prefrontal Cortex

引用

CEREBRAL CORTEX 2017年第12期27卷 5663-5671页

作者： Tiganj, Zoran Jung, Min Whan Kim, Jieun Howard, Marc W. Boston Univ Ctr Memory & Brain Dept Psychol & Brain Sci Boston MA 02215 USA Inst for Basic Sci Korea Ctr Synapt Brain Dysfunct Daejeon South Korea Korea Adv Inst Sci & Technol Dept Biol Sci Daejeon South Korea

A subset of hippocampal neurons, known as "time cells" fire sequentially for circumscribed periods of time within a delay interval. We investigated whether medial prefrontal cortex (mPFC) also contains time cells and whether their qualitative properties differ from those in the hippocampus and striatum. We studied the firing correlates of neurons in the rodent mPFC during a temporal discrimination task. On each trial, the animals waited for a few seconds in the stem of a T-maze. A subpopulation of units fired in a sequence consistently across trials for a circumscribed period during the delay interval. These sequentially activated time cells showed temporal accuracy that decreased as time passed as measured by both the width of their firing fields and the number of cells that fired at a particular part of the interval. The firing dynamics of the time cells was significantly better explained with the elapse of time than with the animals' position and velocity. The findings observed here in the mPFC are consistent with those previously reported in the hippocampus and striatum, suggesting that the sequentially activated time cells are not specific to these areas, but are part of a common representational motif across regions.

关键词： mPFC sequential coding time cells

来源：评论

学校读者我要写书评

暂无评论

Selecting an optimal instrument to identify active ingredients of the motivational interviewing-process

引用

JOURNAL OF PSYCHOSOMATIC RESEARCH 2015年第3期78卷 268-276页

作者： Dobber, Jos van Meijel, Berno Barkhof, Emile op Reimer, Wilma Scholte Latour, Corine Peters, Ron Linszen, Don Amsterdam Univ Appl Sci Amsterdam Sch Hlth Profess NL-1105 BD Amsterdam Netherlands Inholland Univ Appl Sci Dept Hlth Sports & Welf Cluster Nursing Amsterdam Netherlands Parnassia Acad Parnassia Psychiat Inst The Hague Netherlands Univ Amsterdam Acad Med Ctr Dept Psychiat NL-1105 AZ Amsterdam Netherlands Vrije Univ Amsterdam Med Ctr Dept Psychiat EGO Inst Hlth & Care Res Amsterdam Netherlands Univ Amsterdam Acad Med Ctr Dept Cardiol NL-1105 AZ Amsterdam Netherlands

Objective: Motivational Interviewing (MI) can effectively stimulate motivation for health behavior change, but the active ingredients of MI are not well known. To help clinicians further stimulate motivation, they need to know the active ingredients of MI. A psychometrically sound instrument is required to identify those ingredients. The purpose of this study is to describe and evaluate the capability of existing instruments to reliably measure one or more potential active ingredients in the MI process between clients and MI-therapists. Methods: We systematically searched MedLine, Embase, Cinahl, Psyclnfo, Cochrane Central, specialised websites and reference lists of selected articles. Results: We found 406 papers, 60 papers were retrieved for further evaluation, based on prespecified criteria. Seventeen instruments that were specifically designed to measure MI or aspects of MI were identified. Fifteen papers met all inclusion criteria, and reported on seven instruments that assess potential active ingredients of the interactive MI process. The capability of these instruments to measure potential active ingredients in detail and as a part of the interactive MI process varies considerably. Three of these instruments measure one or more potential active ingredients in a reliable and valid way. Conclusion: To identify the potential active ingredients in the interactive MI process, a combination of the SCOPE (which measures potential technical active ingredients) and the GROMIT or the global ratings of the MISC2 (to measure potential relational ingredients) seems favourable. (C) 2014 Elsevier Inc. All rights reserved.

关键词： Motivational interviewing Therapy process sequential coding

来源：评论

学校读者我要写书评

暂无评论

Within-session communication patterns predict alcohol treatment outcomes

引用

DRUG AND ALCOHOL DEPENDENCE 2015年 157卷 205-209页

作者： Houck, Jon M. Moyers, Theresa B. Univ New Mexico Dept Psychol Ctr Alcoholism Subst Abuse & Addict Albuquerque NM 87131 USA

Background: Within-session client speech is theorized to be a key mechanism of behavior change in motivational interviewing (MI), a directional, client-centered approach to behavior change. Client change talk (CT: speech indicating movement toward changing a problematic health behavior) and sustain talk (ST: speech supporting continuing a problematic health behavior) have each shown relationships with outcomes. However, it may be the case that patterns of within-session client speech, rather than counts of client speech, are important for producing change. Methods: Recorded initial MI/MET psychotherapy sessions from Project MATCH had been previously rated using the Motivational Interviewing sequential Code for Observing Process Exchange (MI-SCOPE), a mutually exclusive and exhaustive sequential coding system. From these existing data, session conditional probabilities for transitions of interest (the transition from CT to more CT, and the transition from reflections of CT to CT) were analyzed as empirical Bayes estimates of log-normalized odds ratios. Results: CT frequencies and these log-normalized odds ratios were entered as independent variables into longitudinal generalized estimating equation (GEE) models predicting within-treatment and post-treatment drinking. While all variables were significant predictors of within-treatment drinking, only the CT-CT transition emerged as a significant predictor of decreased drinking after treatment. Conclusions: The momentum of a client's speech about change during an MI session may be a better predictor of outcome than is a simple frequency count of it. Attending not only to the mere occurrence of CT, but also recognizing the importance of consecutive client statements of CT, may improve treatment outcomes. (C) 2015 Elsevier Ireland Ltd. All rights reserved.

关键词： Mechanisms of behavior change Psychotherapy process Motivational interviewing sequential coding

来源：评论

学校读者我要写书评

暂无评论

Improved Upper Bounds to the Causal Quadratic Rate-Distortion Function for Gaussian Stationary Sources

引用

IEEE TRANSACTIONS ON INFORMATION THEORY 2012年第5期58卷 3131-3152页

作者： Derpich, Milan S. Ostergaard, Jan Univ Tecn Federico Santa Maria Dept Elect Engn Valparaiso Chile Aalborg Univ Dept Elect Syst DK-9220 Aalborg Denmark

We improve the existing achievable rate regions for causal and for zero-delay source coding of stationary Gaussian sources under an average mean squared error distortion measure. To begin with, we find a closed-form expression for the information-theoretic causal rate-distortion function (RDF) under such distortion measure, denoted by R-c(it)(D), for first-order Gauss-Markov processes. R-c(it)(D) is a lower bound to the optimal performance theoretically attainable (OPTA) by any causal source code, namely R-c(it)(D). We show that, for Gaussian sources, the latter can also be upper bounded as R-c(op)(D) <= R-c(it)(D) + 0.5 log(2) (2 pi e) bits/sample. In order to analyze R-c(it)(D) for arbitrary zero-mean Gaussian stationary sources, we introduce <(R-c(it))over bar>(D), the information-theoretic causal RDF when the reconstruction error is jointly stationary with the source. Based upon <(R-c(it))over bar>(D), we derive three closed-form upper bounds to the additive rate loss defined as <(R-c(it))over bar>(D) - R(D), where R(D) denotes Shannon's RDF. Two of these bounds are strictly smaller than 0.5 bits/sample at all rates. These bounds differ from one another in their tightness and ease of evaluation;the tighter the bound, the more involved its evaluation. We then show that, for any source spectral density and any positive distortion D <= sigma(2)(x), <(R-c(it))over bar>(D) can be realized by an additive white Gaussian noise channel surrounded by a unique set of causal pre-, post-, and feedback filters. We show that finding such filters constitutes a convex optimization problem. In order to solve the latter, we propose an iterative optimization procedure that yields the optimal filters and is guaranteed to converge to <(R-c(it))over bar>(D). Finally, by establishing a connection to feedback quantization, we design a causal and a zero-delay coding scheme which, for Gaussian sources, achieves an operational rate lower than <(R-c(it))over bar>(D) + 0.254 and <(R-c(it))ov

关键词： Causality convex optimization differential pulse-code modulation entropy coded dithered quantization (ECDQ) noise-shaping rate-distortion theory sequential coding

来源：评论

学校读者我要写书评

暂无评论

A Secure Video Steganography with Encryption Based on LSB Technique

A Secure Video Steganography with Encryption Based on LSB Te...

引用

IEEE International Conference on Computational Intelligence and Computing Research (ICCIC)

作者： Yadav, Pooja Mishra, Nishchol Sharma, Sanjeev Rajiv Gandhi Proudyogiki Vishwavidyalaya Sch Informat Technol Bhopal India

ISBN: (纸本)9781479915941;9781479915958

Need of hiding information from intruders has been around since ancient times. Nowadays Digital media is getting advanced like text, image, audio, video etc. To maintain the secrecy of information, different methods of hiding have been evolved. One of them is Steganography, which means hiding information under some other information without noticeable change in cover information. Recently Video Steganography has become a boon for providing large amount of data to be transferred secretly. Video is simply a sequence of images, hence much space is available in between for hiding information. In proposed scheme video steganography is used to hide a secret video stream in cover video stream. Each frame of secret video will be broken into individual components then converted into 8-bit binary values, and encrypted using XOR with secret key and encrypted frames will be hidden in the least significant bit of each frames using sequential encoding of Cover video. To enhance more security each bit of secret frames will be stored in cover frames following a pattern BGRRGBGR.

关键词： Encryption Image steganography sequential coding Video Steganography

来源：评论

学校读者我要写书评

暂无评论

Improved Upper Bounds to the Causal Quadratic Rate-Distortion Function for Gaussian Stationary Sources

Improved Upper Bounds to the Causal Quadratic Rate-Distortio...

引用

2010 IEEE International Symposium on Information Theory

作者： Derpich, Milan S. Ostergaard, Jan Univ Tecn Federico Santa Maria Dept Elect Engn Valparaiso Chile Aalborg Univ Dept Elect Syst DK-9220 Aalborg Denmark

ISBN: (纸本)9781424469604

We improve the existing achievable rate regions for causal and for zero-delay source coding of stationary Gaussian sources for mean squared error (MSE) distortion. First, we define the information-theoretic causal rate-distortion function (RDF), R-c(it) (D). In order to analyze R-c(it)(D), we introduce <(R-c(it))over bar> (D), the information theoretic causal RDF when reconstruction error is jointly stationary with the source. Based upon <(R-c(it))over bar> (D), we derive four closed form upper bounds to the gap between <(R-c(it))over bar> (D) and Shannon's RDF, two of them strictly smaller than 0.5 bits/sample at all rates. We then show that <(R-c(it))over bar> (D) can be realized by an AWGN channel surrounded by a unique set of causal pre-, post-, and feedback filters. We show that finding such filters constitutes a convex optimization problem and propose an iterative procedure to solve it. Finally, we build upon <(R-c(it))over bar> (D) to improve existing bounds on the optimal performance attainable by causal and zero-delay codes.

关键词： Causality rate-distortion theory entropy coded dithered quantization noise-shaping differential pulse-code modulation (DPCM) sequential coding convex optimization

来源：评论

学校读者我要写书评

暂无评论

Successive coding strategy in the m-helper problem

Successive coding strategy in the <i>m-helper</i> problem

引用

IEEE International Symposium on Information Theory

作者： Behroozi, Hamid Soleymani, M. Reza Concordia Univ Elect & Comp Engn Dept Montreal PQ Canada

ISBN: (纸本)9781424405053

We evaluate the performance of the successive coding strategy for the problem of multiterminal lossy coding of correlated Gaussian sources. We consider the m-helper problem for the special case of m = 1 where one source provides partial side information to the decoder to help reconstruction of the main source signal. Our results reconfirm the fact that the successive coding strategy is an optimal strategy in sense of achieving the rate-distortion function of the 1-helper problem. Comparing the performance of the sequential coding with the performance of the successive coding, we show that there is no sum rate loss when the side information is not available at the encoder. Finally, based on the successive coding strategy, we provide an achievable rate-distortion region for the m-helper problem.

关键词： multiterminal source coding partial side information rate-distortion region successive coding sequential coding

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：