Recent Advances in Steganography

Steganography is the art and science of communicating which hides the existence of the communication. Steganographic technologies are an important part of the future of Internet security and privacy on open systems such as the Internet. This book's focus is on a relatively new field of study in Steganography and it takes a look at this technology by introducing the readers various concepts of Steganography and Steganalysis. The book has a brief history of steganography and it surveys steganalysis methods considering their modeling techniques. Some new steganography techniques for hiding secret data in images are presented. Furthermore, steganography in speeches is reviewed, and a new approach for hiding data in speeches is introduced

Hybrid solutions to instantaneous MIMO blind separation and decoding: narrowband, QAM and square cases

Future wireless communication systems are desired to support high data rates and high quality transmission when considering the growing multimedia applications. Increasing the channel throughput leads to the multiple input and multiple output and blind equalization techniques in recent years. Thereby blind MIMO equalization has attracted a great interest.Both system performance and computational complexities play important roles in real time communications. Reducing the computational load and providing accurate performances are the main challenges in present systems. In this thesis, a hybrid method which can provide an affordable complexity with good performance for Blind Equalization in large constellation MIMO systems is proposed first. Saving computational cost happens both in the signal sep- aration part and in signal detection part. First, based on Quadrature amplitude modulation signal characteristics, an efficient and simple nonlinear function for the Independent Compo- nent Analysis is introduced. Second, using the idea of the sphere decoding, we choose the soft information of channels in a sphere, and overcome the so- called curse of dimensionality of the Expectation Maximization (EM) algorithm and enhance the final results simultaneously. Mathematically, we demonstrate in the digital communication cases, the EM algorithm shows Newton -like convergence.Despite the widespread use of forward -error coding (FEC), most multiple input multiple output (MIMO) blind channel estimation techniques ignore its presence, and instead make the sim- plifying assumption that the transmitted symbols are uncoded. However, FEC induces code structure in the transmitted sequence that can be exploited to improve blind MIMO channel estimates. In final part of this work, we exploit the iterative channel estimation and decoding performance for blind MIMO equalization. Experiments show the improvements achievable by exploiting the existence of coding structures and that it can access the performance of a BCJR equalizer with perfect channel information in a reasonable SNR range. All results are confirmed experimentally for the example of blind equalization in block fading MIMO systems

Algorithms for Blind Equalization Based on Relative Gradient and Toeplitz Constraints

Blind Equalization (BE) refers to the problem of recovering the source symbol sequence from a signal received through a channel in the presence of additive noise and channel distortion, when the channel response is unknown and a training sequence is not accessible. To achieve BE, statistical or constellation properties of the source symbols are exploited. In BE algorithms, two main concerns are convergence speed and computational complexity. In this dissertation, we explore the application of relative gradient for equalizer adaptation with a structure constraint on the equalizer matrix, for fast convergence without excessive computational complexity. We model blind equalization with symbol-rate sampling as a blind source separation (BSS) problem and study two single-carrier transmission schemes, specifically block transmission with guard intervals and continuous transmission. Under either scheme, blind equalization can be achieved using independent component analysis (ICA) algorithms with a Toeplitz or circulant constraint on the structure of the separating matrix. We also develop relative gradient versions of the widely used Bussgang-type algorithms. Processing the equalizer outputs in sliding blocks, we are able to use the relative gradient for adaptation of the Toeplitz constrained equalizer matrix. The use of relative gradient makes the Bussgang condition appear explicitly in the matrix adaptation and speeds up convergence. For the ICA-based and Bussgang-type algorithms with relative gradient and matrix structure constraints, we simplify the matrix adaptations to obtain equivalent equalizer vector adaptations for reduced computational cost. Efficient implementations with fast Fourier transform, and approximation schemes for the cross-correlation terms used in the adaptation, are shown to further reduce computational cost. We also consider the use of a relative gradient algorithm for channel shortening in orthogonal frequency division multiplexing (OFDM) systems. The redundancy of the cyclic prefix symbols is used to shorten a channel with a long impulse response. We show interesting preliminary results for a shortening algorithm based on relative gradient

Event generation with SHERPA 1.1

In this paper the current release of the Monte Carlo event generator Sherpa, version 1.1, is presented. Sherpa is a general-purpose tool for the simulation of particle collisions at high-energy colliders. It contains a very flexible tree-level matrix-element generator for the calculation of hard scattering processes within the Standard Model and various new physics models. The emission of additional QCD partons off the initial and final states is described through a parton-shower model. To consistently combine multi-parton matrix elements with the QCD parton cascades the approach of Catani, Krauss, Kuhn and Webber is employed. A simple model of multiple interactions is used to account for underlying events in hadron--hadron collisions. The fragmentation of partons into primary hadrons is described using a phenomenological cluster-hadronisation model. A comprehensive library for simulating tau-lepton and hadron decays is provided. Where available form-factor models and matrix elements are used, allowing for the inclusion of spin correlations; effects of virtual and real QED corrections are included using the approach of Yennie, Frautschi and Suura.Comment: 47 pages, 21 figure

An Optimization Theoretical Framework for Resource Allocation over Wireless Networks

With the advancement of wireless technologies, wireless networking has become ubiquitous owing to the great demand of pervasive mobile applications. Some fundamental challenges exist for the next generation wireless network design such as time varying nature of wireless channels, co-channel interferences, provisioning of heterogeneous type of services, etc. So how to overcome these difficulties and improve the system performance have become an important research topic. Dynamic resource allocation is a general strategy to control the interferences and enhance the performance of wireless networks. The basic idea behind dynamic resource allocation is to utilize the channel more efficiently by sharing the spectrum and reducing interference through optimizing parameters such as the transmitting power, symbol transmission rate, modulation scheme, coding scheme, bandwidth, etc. Moreover, the network performance can be further improved by introducing diversity, such as multiuser, time, frequency, and space diversity. In addition, cross layer approach for resource allocation can provide advantages such as low overhead, more efficiency, and direct end-to-end QoS provision. The designers for next generation wireless networks face the common problem of how to optimize the system objective under the user Quality of Service (QoS) constraint. There is a need of unified but general optimization framework for resource allocation to allow taking into account a diverse set of objective functions with various QoS requirements, while considering all kinds of diversity and cross layer approach. We propose an optimization theoretical framework for resource allocation and apply these ideas to different network situations such as: 1.Centralized resource allocation with fairness constraint 2.Distributed resource allocation using game theory 3.OFDMA resource allocation 4.Cross layer approach On the whole, we develop a universal view of the whole wireless networks from multiple dimensions: time, frequency, space, user, and layers. We develop some schemes to fully utilize the resources. The success of the proposed research will significantly improve the way how to design and analyze resource allocation over wireless networks. In addition, the cross-layer optimization nature of the problem provides an innovative insight into vertical integration of wireless networks

Earth Observatory Satellite system definition study. Report no. 3: Design/cost tradeoff studies

The key issues in the Earth Observatory Satellite (EOS) program which are subject to configuration study and tradeoff are identified. The issue of a combined operational and research and development program is considered. It is stated that cost and spacecraft weight are the key design variables and design options are proposed in terms of these parameters. A cost analysis of the EOS program is provided. Diagrams of the satellite configuration and subsystem components are included

Leadership Development: Continuous Improvement through Character Assessment

One of the keys to personal development is self-awareness as assessed by instruments such as the Myers-Briggs Type Indicator (MBTI) and the NEO PI-R, both of which are widely accepted reliable and valid indicators and measures of personality type. However, assessing the part of personality known as character presents challenges that are not adequately addressed by today\u27s popular instruments leaving information needed for development incomplete or unavailable. An instrument that provides a reliable and valid assessment of character for leadership and personal development purposes could be very valuable. Qualitative methods were used for this study to investigate leaders\u27 perceptions of the utility of using an existing instrument, the Temperament and Character Inventory (TCI), to enhance character awareness for the purposes of personal and professional growth and improving leadership skills. This study demonstrates that the TCI can be useful for enhancing such skills and development by helping leaders improve their self-awareness through character assessment. This study included two groups of respondents, the seven member executive group and the three member coaching group. The executive group completed the TCI, received feedback and assistance in developing an action plan, and each participant was interviewed to determine to what extent the TCI and this process was useful to them for improving self-awareness of character and for identifying ways they desired to improve their personal and professional skills. The coaching group participated by both completing their personal TCI process, and by working with selected executive group participants and the researcher in interpreting the executive participants\u27 TO results and advising on action plans. The coaching participants were interviewed to determine their perceptions of the extent to which the TCI and this process were useful to them personally and useful to the executive participants they coached. Additionally, the coaching group was asked to recommend specific training approaches, methods and improvements to make the overall process more effective. This study demonstrated that the TCI and the methods used in the study can be useful for leadership development to those committed to professional and personal growth by using character assessment as part of a personal continuous improvement program. Some participants qualified their endorsement of the TCI and the process used for the study by suggesting changes

Energy and quality scalable wireless communication

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.Includes bibliographical references (p. 165-171).Nodes for emerging, high-density wireless networks will face the dual challenges of continuous, multi-year operation under diverse and challenging operating conditions. The wireless communication subsystem, a substantial consumer of energy, must therefore be designed with unprecedented energy efficiency. To meet this challenge, inefficiencies once overlooked must be addressed, and the system must be designed for energy scalability, the use of graceful energy vs. quality trade-offs in response to continuous variations in operational conditions. Using a comprehensive model framework that unifies cross-disciplinary models for energy consumption and communication performance, this work explores multi-dimensional trade-offs of energy and quality for wireless communication at all levels of the system hierarchy. The circuit-level "knob" of dynamic voltage scaling is implemented on a commercial microprocessor and integrated into a power aware, prototype microsensor node. Power aware abstractions encourage collaboration between the hardware, which fundamentally dissipates the energy, and software, which controls how the hardware behaves. Accurate models of hardware energy consumption reveal inefficiencies of routing techniques such as multihop, and the models are fused with information-theoretic limits on code performance to bound the energy scalability of the hardware platform. An application-specific protocol for microsensor networks is evaluated with a new, interactive Java simulation tool created expressly for energy-conscious, high density wireless networks. Close collaboration between software and hardware layers, and across the research disciplines that compose wireless communication itself, are crucial enablers for energy-efficient wireless communication.by Rex Kee Min.Ph.D

The Role Of Calcium In Mature Osteoblasts Vitamin D Receptor (VDR)-Mediated Activities To Modulate Skeletal Structures And Mineral Content

Vitamin D plays a role in the prevention of rickets in children and osteomalacia in adults. However, direct activity of vitamin D and Vitamin D Receptor (VDR) in bone cells has not been fully understood. Vitamin D receptor activities in bone cells are modulated by the dietary calcium in endocrine and bone paracrine/autocrine pathways in various studies. However, confirmation of direct VDR activities in bone cells in conjunction with calcium interactions on genetically modified animals has not been previously evaluated. Studies in these settings will assist our understanding of Vitamin D activities and VDR physiology in bone cells to modulate bone structures. In chapter 3, a study on the generation and characterisation of transgenic over-expression of VDR in mature osteoblast using the osteocalcin promoter in C57bl6/J background (ObVDR-B6) was conducted. Results of this chapter confirm the anabolic action of this transgene and demonstrate that the VDR activity in mature osteoblasts exerts gender-specific and anatomical specific activities. In chapter 4, the ObVDR-B6 mouse line was subjected to normal dietary calcium and phosphate intakes and extremely low dietary calcium (0.03 %) and phosphate (0.08 %) levels (LowCaP diet) over short term (3w) and long term (17w) periods to investigate its effects on bone mineral and skeletal structure. The study provides evidence that VDR activities in mature osteoblasts are anti-catabolic for skeletal structures with normal dietary calcium/phosphate, but catabolic with extremely low calcium/phosphate diets. Whether deletion of VDR in mature osteoblasts using the Cre/lox-P system and osteocalcin promoter (ObVDR-KO) can rescue the skeletal structure of the mice when fed LowCaP diet is addressed in chapter 5. Results from this study confirmed that the activities of VDR in mature osteoblasts are modulated by the levels of dietary calcium and phosphate. Under normal calcium/phosphate levels, ObVDR-KO bone structures were not different from control mice. However, when fed LowCaP diet, the ObVDR-KO has anomalous bone structure with very high cortical porosity and high serum PTH and 1α,25 dihydroxyvitamin D3 (1,25D) levels. Although these studies and the mouse models have several limitations, overall data have contributed to elucidating the role of VDR activities in mature osteoblasts in skeletal biology and physiology in regards to dietary calcium/phosphate and further strengthen the evidence of the direct activities of VDR in skeletal health and mineral homeostasis. However, skeletal sites, region examined, sex, and age of the animals significantly influenced the results. Therefore, careful adjustment and further studies are needed to reveal the activities of mature osteoblast VDR in both genders, various skeletal sites, age related bone properties and its interaction with dietary calcium/phosphate.Thesis (Ph.D.) -- University of Adelaide, Adelaide Medical School, 201