Miolane, Charlotte Vikkelsø
ensurethat no attack violatesthe securitybounds specifiedbygeneric attack namely exhaustivekey search and table lookup attacks. This thesis contains a general introduction to cryptography with focus on block ciphers and important block cipher designs, in particular the Advanced Encryption Standard...... by an analytic and systematic approach that allows insight to the techniques. Moreover a new procedure of generating and applying probabilistic equations in algebraic attacks on block cipher is proposed and examined. Also, we present practical results, which to our knowledge are the best algebraic results...... on small scale variants of AES. In the final part of the thesis we present a new block cipher proposal Present and examine its security against algebraic and differential cryptanalysis in particular....
The New Block Cipher Design (Tigris Cipher
Omar A. Dawood
2015-11-01
Full Text Available In the present paper we have proposed a new variant of AES cipher with high level of security and an elegant construction called TIGRIS cipher. The TIGRIS name has been derived from one of the two famous rivers in Iraq. The proposed TIGRIS cipher is a revision for the proposed Euphrates cipher which has already been published. It has been designed with a good coherent structure that is based on solid algebraic and well mathematical opinions. The proposed cipher uses the SPN structure and what is known by the Galois Field GF (28. It is an iterated cipher that has a conservative design which is easily implemented on both hardware and software. It operates with block size of 128-bits and with three variable key lengths of 128-bits, 192-bits and 256-bits in addition to sixteen rounds or multiples of four rounds. The proposed cipher works with good invertible operations' stages and a compact duplicated ciphering key. The Tigris cipher construction strategy includes the adoption of construction a new S-box with high non-linearity that uses the same routines of the AES-S-box stage but with different modular arithmetic of irreducible polynomial and different affine matrix in addition to the distinct constant vector. The second and the third layers of the proposed model are based on the shifting concept for the confusion and diffusion process with reversible operations. The last layer of the proposed model is the key addition layer that is responsible for the expanding and generating the ciphering key by two directions those of row and column expansion, which are associated with two constant vectors of golden ratio and base nature algorithm as a fixed word to eliminate any weak or semi-weak ciphering key.
Cryptanalysis of Selected Block Ciphers
Alkhzaimi, Hoda A.
ciphers initiatives, and the Competition for Authenticated Encryption: Security, Applicability, and Robustness (CAESAR). In this thesis, we first present cryptanalytic results on different ciphers. We propose attack named the Invariant Subspace Attack. It is utilized to break the full block cipher...
Benchmarking Block Ciphers for Wireless Sensor Networks
Law, Y.W.; Doumen, J.M.; Hartel, P.H.
2004-01-01
Choosing the most storage- and energy-efficient block cipher specifically for wireless sensor networks (WSNs) is not as straightforward as it seems. To our knowledge so far, there is no systematic evaluation framework for the purpose. We have identified the candidates of block ciphers suitable for W
Benchmarking Block Ciphers for Wireless Sensor Networks
Law, Y.W.; Doumen, J.M.; Hartel, Pieter H.
2004-01-01
Choosing the most storage- and energy-efficient block cipher specifically for wireless sensor networks (WSNs) is not as straightforward as it seems. To our knowledge so far, there is no systematic evaluation framework for the purpose. We have identified the candidates of block ciphers suitable for
Exploring Energy Efficiency of Lightweight Block Ciphers
Banik, Subhadeep; Bogdanov, Andrey; Regazzoni, Francesco
2016-01-01
lightweight block ciphers, and thereby try to predict the optimal value of r at which an r-round unrolled architecture for a cipher is likely to be most energy efficient. We also try to relate our results to some physical design parameters like the signal delay across a round and algorithmic parameters like......In the last few years, the field of lightweight cryptography has seen an influx in the number of block ciphers and hash functions being proposed. One of the metrics that define a good lightweight design is the energy consumed per unit operation of the algorithm. For block ciphers, this operation...... is the encryption of one plaintext. By studying the energy consumption model of a CMOS gate, we arrive at the conclusion that the energy consumed per cycle during the encryption operation of an r-round unrolled architecture of any block cipher is a quadratic function in r. We then apply our model to 9 well known...
Secure Block Ciphers - Cryptanalysis and Design
Tiessen, Tyge
is fundamental to this development and is absolutely essential for all private and corporate communication, ranging from bank transactions, digital citizen services, and remote computer access, to cell phone calls and instant messaging. The vast majority of secured data sent over all types of networks...... is an introduction to block ciphers and their cryptanalysis, the second part contains publications written and published during the PhD studies. The first publication evaluates the security of a modification of the AES in which the choice of S-box is unknown to the attacker. We find that some of the attacks that can...... be applied to the AES can be transferred to this block cipher, albeit with a higher attack complexity. The second publication introduces a new block cipher family which is targeted for new applications in fully homomorphic encryption and multi-party computation. We demonstrate the soundness of the design...
Round Gating for Low Energy Block Ciphers
Banik, Subhadeep; Bogdanov, Andrey; Regazzoni, Francesco;
2016-01-01
Pushed by the pervasive diffusion of devices operated by battery or by the energy harvested, energy has become one of the most important parameter to be optimized for embedded systems. Particularly relevant would be to optimize the energy consumption of security primitives. In this paper we explore...... design techniques for implementing block ciphers in a low energy fashion. We concentrate on round based implementation and we discuss how gating, applied at round level can affect and improve the energy consumption of the most common lightweight block cipher currently used in the internet of things...
Improved cryptanalysis of the block cipher KASUMI
Jia, Keting; Li, Leibo; Rechberger, Christian;
2013-01-01
KASUMI is a block cipher which consists of eight Feistel rounds with a 128-bit key. Proposed more than 10 years ago, the confidentiality and integrity of 3G mobile communications systems depend on the security of KASUMI. In the practically interesting single key setting, only up to 6 rounds have...
Hardware realization of chaos based block cipher for image encryption
Barakat, Mohamed L.
2011-12-01
Unlike stream ciphers, block ciphers are very essential for parallel processing applications. In this paper, the first hardware realization of chaotic-based block cipher is proposed for image encryption applications. The proposed system is tested for known cryptanalysis attacks and for different block sizes. When implemented on Virtex-IV, system performance showed high throughput and utilized small area. Passing successfully in all tests, our system proved to be secure with all block sizes. © 2011 IEEE.
The block cipher NSABC (public domain)
Nguyenova-Stepanikova, Alice
2011-01-01
We introduce NSABC/w -- Nice-Structured Algebraic Block Cipher using w-bit word arithmetic, a 4w-bit analogous of Skipjack [NSA98] with 5w-bit key. The Skipjack's internal 4-round Feistel structure is replaced with a w-bit, 2-round cascade of a binary operation (x,z)\\mapsto(x\\boxdot z)\\lll(w/2) that permutes a text word x under control of a key word z. The operation \\boxdot, similarly to the multiplication in IDEA [LM91, LMM91], bases on an algebraic group over w-bit words, so it is also capable of decrypting by means of the inverse element of z in the group. The cipher utilizes a secret 4w-bit tweak -- an easily changeable parameter with unique value for each block encrypted under the same key [LRW02] -- that is derived from the block index and an additional 4w -bit key. A software implementation for w=64 takes circa 9 clock cycles per byte on x86-64 processors.
Survey and benchmark of block ciphers for wireless sensor networks
Law, Yee Wei; Doumen, Jeroen; Hartel, Pieter
2004-01-01
Choosing the most storage- and energy-efficient block cipher specifically for wireless sensor networks (WSNs) is not as straightforward as it seems. To our knowledge so far, there is no systematic evaluation framework for the purpose. In this paper, we have identified the candidates of block ciphers
Benchmarking Block Ciphers for Wireless Sensor Networks (Extended Abstract)
Law, Y.W.; Doumen, J.M.; Hartel, P.H.
2004-01-01
Choosing the most storage- and energy-efficient block cipher specifically for wireless sensor networks (WSNs) is not as straightforward as it seems. To our knowledge so far, there is no systematic evaluation framework for the purpose. We have identified the candidates of block ciphers suitable for W
Benchmarking Block Ciphers for Wireless Sensor Networks (Extended Abstract)
Law, Y.W.; Doumen, J.M.; Hartel, Pieter H.
2004-01-01
Choosing the most storage- and energy-efficient block cipher specifically for wireless sensor networks (WSNs) is not as straightforward as it seems. To our knowledge so far, there is no systematic evaluation framework for the purpose. We have identified the candidates of block ciphers suitable for
Survey and Benchmark of Block Ciphers for Wireless Sensor Networks
Law, Y.W.; Doumen, J.M.; Hartel, Pieter H.
Choosing the most storage- and energy-efficient block cipher specifically for wireless sensor networks (WSNs) is not as straightforward as it seems. To our knowledge so far, there is no systematic evaluation framework for the purpose. In this paper, we have identified the candidates of block ciphers
High Order Differential Attack and Trace Attack to Block Ciphers
HU Yupu; CHEN Kai; Xiao Guozhen
2001-01-01
In this paper, we prove a high or-der differential property of power function, then giverespectively high order differential attack and traceattack to block ciphers. These attacks depend onlyon block cipher's algebraic shape on GF(2n) and haveno relation with its designing structure. The condi-tions are given for both effective attacks and strengthagainst attacks.
Towards understanding the known-key security of block ciphers
Andreeva, Elena; Bogdanov, Andrey; Mennink, Bart
2014-01-01
ciphers based on ideal components such as random permutations and random functions as well as propose new generic known-key attacks on generalized Feistel ciphers. We introduce the notion of known-key indifferentiability to capture the security of such block ciphers under a known key. To show its...... meaningfulness, we prove that the known-key attacks on block ciphers with ideal primitives to date violate security under known-key indifferentiability. On the other hand, to demonstrate its constructiveness, we prove the balanced Feistel cipher with random functions and the multiple Even-Mansour cipher...... with random permutations known-key indifferentiable for a sufficient number of rounds. We note that known-key indifferentiability is more quickly and tightly attained by multiple Even-Mansour which puts it forward as a construction provably secure against known-key attacks....
Observations on the SIMON Block Cipher Family
Kölbl, Stefan; Leander, Gregor; Tiessen, Tyge
2015-01-01
In this paper we analyse the general class of functions underlying the Simon block cipher. In particular, we derive efficiently computable and easily implementable expressions for the exact differential and linear behaviour of Simon-like round functions. Following up on this, we use those...... expressions for a computer aided approach based on SAT/SMT solvers to find both optimal differential and linear characteristics for Simon. Furthermore, we are able to find all characteristics contributing to the probability of a differential for Simon32 and give better estimates for the probability for other...... variants. Finally, we investigate a large set of Simon variants using different rotation constants with respect to their resistance against differential and linear cryptanalysis. Interestingly, the default parameters seem to be not always optimal....
Counting equations in algebraic attacks on block ciphers
Knudsen, Lars Ramkilde; Miolane, Charlotte Vikkelsø
2010-01-01
This paper is about counting linearly independent equations for so-called algebraic attacks on block ciphers. The basic idea behind many of these approaches, e.g., XL, is to generate a large set of equations from an initial set of equations by multiplication of existing equations by the variables...... independent equations which can be generated in algebraic attacks within each of these sets of a certain degree. While this does not give us a direct formula for the success of algebraic attacks on block ciphers, it gives some interesting bounds on the number of equations one can obtain from a given block...... to the algebraic attacks as defined here....
Design of Optimal Diffusion Layers for SPN Block Ciphers
CUI Ling-guo; CAO Yuan-da
2006-01-01
The diffusion layers in substitution-permutation network(SPN) block ciphers are almost invertible linear transformations, which is optimal if the branch number reaches the maximum value. The method of constructing involutory optimal diffusion layers is proposed based on the Cauchy matrix, which can decrease the cost of implementation. The analysis to experimental results indicates that the diffusion layer ensures the security of the SPN block cipher against differential cryptanalysis(DC) and linear cryptanalysis(LC), and decreases half the cost of implementation.
Modified Hill Cipher for a Large Block of Plaintext with Interlacing and Iteration
V. U.K. Sastry
2008-01-01
Full Text Available In this research, we have developed a large block cipher by modifying the Hill cipher. In this, we have introduced interlacing of the binary bits of the plaintext as the primary concept leading to confusion. This process is strengthened by using iteration. The cryptanalysis and avalanche effect mentioned in this research clearly exhibit the strength of the cipher.
Improved Linear Attacks on the Chinese Block Cipher Standard
刘明洁; 陈佳哲
2014-01-01
The block cipher used in the Chinese Wireless LAN Standard (WAPI), SMS4, was recently renamed as SM4, and became the block cipher standard issued by the Chinese government. This paper gives a method for finding the linear approximations of SMS4. With this method, 19-round one-dimensional approximations are given, which are used to improve the previous linear cryptanalysis of SMS4. The 19-round approximations hold with bias 2−62.27; we use one of them to leverage a linear attack on 23-round SMS4. Our attack improves the previous 23-round attacks by reducing the time complexity. Furthermore, the data complexity of our attack is further improved by the multidimensional linear approach.
A 64 Bits Rotor Enhanced Block Cipher (Rebc3
Ahmed ElShafee
2013-04-01
Full Text Available This paper gives a new proposed cryptosystem (REBC3 that is designed to take advantages of the new generation of 64bits microprocessors which commercially known as x64 systems. The old version REBC2,which was published in Africon 2007. REBC2 was basically developed for the 32bits microprocessors which is commercially known as x86 systems. REBC3 like REBC2 use the concept of rotor enhanced blockcipher which was initially proposed by the author in [NRSC 2002] on the first version of REBC. REBC2 used the same concept from a another point of view, which is using rotors to achieve two basiccryptographic operations; permutation, and substitution. Round key is generated using rotor too, which is used to achieve ciphertext key dependency. To enhance non-linearity and to resist linear cryptanalysis,REBC3 has a variable block, and key lengths. Each round has its own block length which depends on round the key and round key length. Dependency is based upon the previous round generated key. Rotors implemented using successive affine transformation . The 32 bits version was proposed in KAMFEE cipher, then the 64bits version was proposed in KAMFEE-X64 cipher. This achieved memory-less, normalized ciphertext statistics, and small processing speed trend. The strength of this system is compared with the REBC2 and RIJNDAEL (AES ciphers.REBC3 cipher gives excellent results from security characteristics and statistical point of view of. So authors suggests to use REBC3 in the area of banking and electronic fund transfer.
Optical design of cipher block chaining (CBC) encryption mode by using digital holography
Gil, Sang Keun; Jeon, Seok Hee; Jung, Jong Rae; Kim, Nam
2016-03-01
We propose an optical design of cipher block chaining (CBC) encryption by using digital holographic technique, which has higher security than the conventional electronic method because of the analog-type randomized cipher text with 2-D array. In this paper, an optical design of CBC encryption mode is implemented by 2-step quadrature phase-shifting digital holographic encryption technique using orthogonal polarization. A block of plain text is encrypted with the encryption key by applying 2-step phase-shifting digital holography, and it is changed into cipher text blocks which are digital holograms. These ciphered digital holograms with the encrypted information are Fourier transform holograms and are recorded on CCDs with 256 gray levels quantized intensities. The decryption is computed by these encrypted digital holograms of cipher texts, the same encryption key and the previous cipher text. Results of computer simulations are presented to verify that the proposed method shows the feasibility in the high secure CBC encryption system.
Design and Analysis of New Symmetric Block Cipher Algorithm
KALAICHELVI V
2015-10-01
Full Text Available Cryptography provides many methods and techniques for secure communication. Currently there are many encryption/decryption algorithms such as DES, AES (Rijndael, Blowfish, etc., are published. However, they are fairly complex and require that one spend a lot of time to comprehend and implement them. This paper introduces simple encryption /decryption algorithm that works fast and fairly secure. In this paper, a new symmetric block cipher algorithm has been developed and is compared with the existing popular algorithms. Simulation results are given to demonstrate the effectiveness of each algorithm. Blowfish and the newly developed algorithms exhibit better performance than other popular existing algorithms.
Efficient configurations for block ciphers with unified ENC/DEC paths
Banik, Subhadeep; Bogdanov, Andrey; Regazzoni, Francesco
2017-01-01
Block Ciphers providing the combined functionalities of encryption and decryption are required to operate in modes of operation like CBC and ELmD. Hence such architectures form critical building blocks for secure cryptographic implementations. Depending on the algebraic structure of a given cipher...
A chaotic block cipher algorithm for image cryptosystems
Amin, Mohamed; Faragallah, Osama S.; Abd El-Latif, Ahmed A.
2010-11-01
Recently, many scholars have proposed chaotic cryptosystems in order to promote communication security. However, there are a number of major problems detected in some of those schemes such as weakness against differential attack, slow performance speed, and unacceptable data expansion. In this paper, we introduce a new chaotic block cipher scheme for image cryptosystems that encrypts block of bits rather than block of pixels. It encrypts 256-bits of plainimage to 256-bits of cipherimage within eight 32-bit registers. The scheme employs the cryptographic primitive operations and a non-linear transformation function within encryption operation, and adopts round keys for encryption using a chaotic system. The new scheme is able to encrypt large size of images with superior performance speed than other schemes. The security analysis of the new scheme confirms a high security level and fairly uniform distribution.
A Public Key Block Cipher Based on Multivariate Quadratic Quasigroups
Gligoroski, Danilo; Knapskog, Svein Johan
2008-01-01
We have designed a new class of public key algorithms based on quasigroup string transformations using a specific class of quasigroups called multivariate quadratic quasigroups (MQQ). Our public key algorithm is a bijective mapping, it does not perform message expansions and can be used both for encryption and signatures. The public key consist of n quadratic polynomials with n variables where n=140, 160, ... . A particular characteristic of our public key algorithm is that it is very fast and highly parallelizable. More concretely, it has the speed of a typical modern symmetric block cipher - the reason for the phrase "A Public Key Block Cipher" in the title of this paper. Namely the reference C code for the 160-bit variant of the algorithm performs decryption in less than 11,000 cycles (on Intel Core 2 Duo -- using only one processor core), and around 6,000 cycles using two CPU cores and OpenMP 2.0 library. However, implemented in Xilinx Virtex-5 FPGA that is running on 249.4 MHz it achieves decryption thro...
PRINCE - A Low-Latency Block Cipher for Pervasive Computing Applications: Extended Abstract
Borghoff, J.; Canteaut, Anne Michele; Guneysu, T.;
2012-01-01
his paper presents a block cipher that is optimized with respect to latency when implemented in hardware. Such ciphers are desirable for many future pervasive applications with real-time security needs. Our cipher, named PRINCE, allows encryption of data within one clock cycle with a very...... competitive chip area compared to known solutions. The fully unrolled fashion in which such algorithms need to be implemented calls for innovative design choices. The number of rounds must be moderate and rounds must have short delays in hardware. At the same time, the traditional need that a cipher has...
Triple SV: A Bit Level Symmetric Block-Cipher Having High Avalanche Effect
Rajdeep Chakraborty
2011-08-01
Full Text Available The prolific growth of network communication system entails high risk of breach in information security. This substantiates the need for higher security for electronic information. Cryptography is one of the ways to secure electronic documents. In this paper, we propose a new block cipher, TRIPLE SV (3SV, with 256-bit block size and 112-bit key length. Generally, stream ciphers produce higher avalanche effect but Triple SV shows a substantial rise in avalanche effect with a block cipher implementation. The CBC mode has been used to attain higher avalanche effect. The technique is implemented in C language and has been tested for feasibility
Block Cipher Involving Key Based Random Interlacing and Key Based Random Decomposition
K. A. Kumar
2010-01-01
Full Text Available Problem statement: The strength of the block ciphers depend on the degree of confusion and diffusion induced in the cipher. Most of the transformations used for this purpose are well known to every one and can be broken by a crypt analyzer. Therefore, in order to counter attack the crypt analyzer, there is a need for better transformations in addition to the existing one. Approach: We tried to use key based random interlacing and key based random decomposition for this purpose. So that, a crypt analyzer cannot understand how interlacing and decomposition is done in every round unless the key is known. Results: The strength of the cipher is assessed by avalanche effect which is proved to be satisfactory. Conclusion/Recommendations: Key based random interlacing and decomposition can be used for introducing confusion and diffusion in block ciphers. The cryptanalysis carried out in this regard shows that the cipher cannot be broken by any cryptanalytic attack.
A 3-Subset Meet-in-the-Middle Attack: Cryptanalysis of the Lightweight Block Cipher KTANTAN
Bogdanov, Andrey; Rechberger, Christian
2011-01-01
In this paper we describe a variant of existing meet-in-the-middle attacks on block ciphers. As an application, we propose meet-in-the-middle attacks that are applicable to the KTANTAN family of block ciphers accepting a key of 80 bits. The attacks are due to sonic weaknesses in its bitwise key s...... requirements, these attacks are valid even in RFID-like environments where only a very limited amount of text material may be available to an attacker....
Cryptanalysis of Lin et al.'s Efficient Block-Cipher-Based Hash Function
Liu, Bozhong; Gong, Zheng; Chen, Xiaohong; Qiu, Weidong; Zheng, Dong
2010-01-01
Hash functions are widely used in authentication. In this paper, the security of Lin et al.'s efficient block-cipher-based hash function is reviewed. By using Joux's multicollisions and Kelsey et al.'s expandable message techniques, we find the scheme is vulnerable to collision, preimage and second
Boura, Christina; Canteaut, Anne; Knudsen, Lars Ramkilde
2017-01-01
study the necessary properties for this coupling permutation. Special care has to be taken of some related-key distinguishers since, in the context of reflection ciphers, they may provide attacks in the single-key setting.We then derive some criteria for constructing secure reflection ciphers...... and analyze the security properties of different families of coupling permutations. Finally, we concentrate on the case of reflection block ciphers and, as an illustration, we provide concrete examples of key schedules corresponding to several coupling permutations, which lead to new variants of the block...
Siswantyo, Sepha; Susanti, Bety Hayat
2016-02-01
Preneel-Govaerts-Vandewalle (PGV) schemes consist of 64 possible single-block-length schemes that can be used to build a hash function based on block ciphers. For those 64 schemes, Preneel claimed that 4 schemes are secure. In this paper, we apply length extension attack on those 4 secure PGV schemes which use RC5 algorithm in its basic construction to test their collision resistance property. The attack result shows that the collision occurred on those 4 secure PGV schemes. Based on the analysis, we indicate that Feistel structure and data dependent rotation operation in RC5 algorithm, XOR operations on the scheme, along with selection of additional message block value also give impact on the collision to occur.
2012-01-01
Cryptography is the study of mathematical techniques that ensure the confidentiality and integrity of information. This relatively new field started out as classified military technology, but has now become commonplace in our daily lives. Cryptography is not only used in banking cards, secure websites and electronic signatures, but also in public transport cards, car keys and garage door openers.Two building blocks in the domain of cryptography are block ciphers and (cryptographic) hash funct...
Spiking Neurons with ASNN Based-Methods for the Neural Block Cipher
Al-Omari, Saleh Ali K
2010-01-01
Problem statement: This paper examines Artificial Spiking Neural Network (ASNN) which inter-connects group of artificial neurons that uses a mathematical model with the aid of block cipher. The aim of undertaken this research is to come up with a block cipher where by the keys are randomly generated by ASNN which can then have any variable block length. This will show the private key is kept and do not have to be exchange to the other side of the communication channel so it present a more secure procedure of key scheduling. The process enables for a faster change in encryption keys and a network level encryption to be implemented at a high speed without the headache of factorization. Approach: The block cipher is converted in public cryptosystem and had a low level of vulnerability to attack from brute, and moreover can able to defend against linear attacks since the Artificial Neural Networks (ANN) architecture convey non-linearity to the encryption/decryption procedures. Result: In this paper is present to ...
Differential Attack on Five Rounds of the SC2000 Block Cipher
Ji-Qiang Lv
2011-01-01
The SC2000 block cipher has a 128-bit block size and a user key of 128,192 or 256 bits,which employs a total of 6.5 rounds if a 128-bit user key is used.It is a CRYPTREC recommended e-government cipher in Japan.In this paper we address how to recover the user key from a few subkey bits of SC2000,and describe two 4.75-round differential characteristics with probability 2-126 of SC2000 and seventy-six 4.75-round differential characteristics with probability 2-127.Finally,we present a differential cryptanalysis attack on a 5-round reduced version of SC2000 when used with a 128-bit key; the attack requires 2125.68 chosen plaintexts and has a time complexity of 212575 5-round SC2000 encryptions.The attack does not threat the security of the full SC2000 cipher,but it suggests for the first time that the safety margin of SC2000 with a 128-bit key decreases below one and a half rounds.
Cryptanalysis of Block Ciphers with Probabilistic Non-Linear Relations of Low Degree
Jakobsen, Thomas
1998-01-01
(x,y)=0$ between plaintext $x$ and ciphertext $y$ that hold with small probability $\\mu$.The second attack needs access to $n=(2m/\\mu)^2$ plaintext/ciphertext pairs where $m=\\deg p$ and its running time is also polynomial in $n$. As a demonstration, we break up to 10 rounds of a cipher constructed...... employed is essentially Sudan's algorithm for decoding Reed-Solomon codes beyond the error-correction diameter. The known-plaintext attack needs $n=2m/\\mu^2$ plaintext/ciphertext pairs and the running time is polynomial in $n$.Furthermore, it is shown how to discover more general non-linear relations $p...... by Nyberg and Knudsen provablysecure against differential and linear cryptanalysis.Key words: Cryptanalysis, block cipher, interpolation attack, non-linear relations, Reed-Solomon codes, Sudan's algorithm....
MICRO ROTOR ENHANCED BLOCK CIPHER DESIGNED FOR EIGHT BITS MICRO-CONTROLLERS (MREBC
Ahmed ElShafee
2013-09-01
Full Text Available The sensor network is a wireless network environment that consists of the many sensors of lightweight and low-power. Authentication between nodes is very vital for network reliability and the integrity ofinformation collected by these nodes. Therefore, encryption algorithm for the implementation of reliable sensor network environments is required to the applicable sensor network. This paper gives a newproposed cryptosystem (MREBC that is designed for 8 bits microcontroller systems. MREBC uses the concept of rotor enhanced block cipher which was initially proposed by the author in [NRSC 2002] on the first version of REBC. MREBC uses rotors to achieve two basic cryptographic operations; permutation,and substitution. Round key is generated using rotor too, which is used to achieve ciphertext key dependency. Rotors implemented using 8 bits successive affine transformation, which achieves memoryless,normalized ciphertext statistics, and small processing speed trend. The strength of this system is compared with the RIJNDAEL (AES cipher. MREBC cipher gives excellent results from security characteristics and statistical point of view of. communication efficiency of MREBC is compared with AESthrough measuring performance by plaintext size, and cost of operation per hop according to the network scale. Arduino microcontroller board is used to implement both MREBC, and AES in order to compare the performance of algorithms. Authors suggests to use MREBC to implement a reliable sensor network environments.
分组密码Cache攻击技术研究%Cache Attacks on Block Ciphers
赵新杰; 王韬; 郭世泽; 刘会英
2012-01-01
近年来,Cache攻击已成为微处理器上分组密码实现的最大安全威胁,相关研究是密码旁路攻击的热点问题.对分组密码Cache攻击进行了综述.阐述了Cache工作原理及Cache命中与失效旁路信息差异,分析了分组密码查表Cache访问特征及泄露信息,从攻击模型、分析方法、研究进展3个方面评述了典型的分组密码Cache攻击技术,并对Cache攻击的发展特点进行了总结,最后指出了该领域研究存在的问题,展望了未来的研究方向.%In recent years, cache attack has become one of the most threatening attacks to block ciphers that implemented on microprocessors. The research in this area is a hot spot of cryptographic side channel attacks. This paper summarizes the cache attacks on block ciphers. The mechanism of cache and the side channel information difference of cache hit/miss are described. The characteristics of cache accesses and corresponding information leakages are analyzed. Several typical cache attack techniques on block ciphers are well discussed from the aspects of attack model, analysis method, research progress. Finally, the features of cache attacks are summarized, the current research pitfalls are provided, and the future directions of cache attacks are given.
A Block Cipher using Rotation and Logical XOR Operations
D. Sravan Kumar
2011-11-01
Full Text Available Cryptography is the study of methods of sending messages in disguised form so that only the intended recipients can remove the disguise and read the messages. Information security has become a very critical aspect of modern communication systems. With the global acceptance of the Internet as a medium of communication, virtually every computer in the world is connected to every other. It has created a new risk for the users of the computers with a constant threat of being hacked and being victims of data theft. In this connection data encryption has become an essential part of secure communication of the messages. In the present paper we propose a new method of encryption of data in blocks using the operations Rotation and Logical XOR.
A Block Cipher using Rotation and Logical XOR Operations
Kumar, D Sravana; Chandrasekhar, A
2012-01-01
Cryptography is the study of methods of sending messages in disguised form so that only the intended recipients can remove the disguise and read the messages. Information security has become a very critical aspect of modern communication systems. With the global acceptance of the Internet as a medium of communication, virtually every computer in the world is connected to every other. It has created a new risk for the users of the computers with a constant threat of being hacked and being victims of data theft. In this connection data encryption has become an essential part of secure communication of the messages. In the present paper we propose a new method of encryption of data in blocks using the operations Rotation and Logical XOR
Wen, Long; Wang, Meiqin; Bogdanov, Andrey
2014-01-01
HIGHT is a block cipher designed in Korea with the involvement of Korea Information Security Agency. It was proposed at CHES 2006 for usage in lightweight applications such as sensor networks and RFID tags. Lately, it has been adopted as ISO standard. Though there is a great deal of cryptanalytic...... results on HIGHT, its security evaluation against the recent zero-correlation linear attacks is still lacking. At the same time, the Feistel-type structure of HIGHT suggests that it might be susceptible to this type of cryptanalysis. In this paper, we aim to bridge this gap. We identify zero......-correlation linear approximations over 16 rounds of HIGHT. Based upon those, we attack 27-round HIGHT (round 4 to round 30) with improved time complexity and practical memory requirements. This attack of ours is the best result on HIGHT to date in the classical single-key setting. We also provide the first attack...
Parallelizable and Authenticated Online Ciphers
Andreeva, Elena; Bogdanov, Andrey; Luykx, Atul
2013-01-01
-purpose CPUs or dedicated hardware.We propose the first parallelizable online cipher, COPE. It performs two calls to the underlying block cipher per plaintext block and is fully parallelizable in both encryption and decryption. COPE is proven secure against chosenplaintext attacks assuming the underlying block......Online ciphers encrypt an arbitrary number of plaintext blocks and output ciphertext blocks which only depend on the preceding plaintext blocks. All online ciphers proposed so far are essentially serial, which significantly limits their performance on parallel architectures such as modern general...
NEW APPROACH IN SYMMETRIC BLOCK CIPHER SECURITY USING A NEW CUBICAL TECHNIQUE
Ali M Alshahrani
2015-02-01
Full Text Available Cryptography is a security technique that must be applied in both communication sides to protect the data during its transmission through the network from all kinds of attack. On the sender side, the original data will be changed into different symbols or shapes by using a known key; this is called encryption. On the other communication side, the decryption process will be done and the data will be returned to its former shape by using the agreed key. The importance of cryptography is to fulfil the communication security requirements. Real time applications (RTA are vulnerable for the moment because of their big size. However, some of the current algorithms are not really appropriate for use with these kinds of information. In this paper, a novel symmetric block cipher cryptography algorithm has been illustrated and discussed. The system uses an 8x8x8 cube, and each cell contains a pair of binary inputs. The cube can provide a huge number of combinations that can produce a very strong algorithm and a long key size. Due to the lightweight and fast technique used in this idea, it is expected to be extremely rapid compared to the majority of current algorithms, such as DES and AES.
The SKINNY Family of Block Ciphers and Its Low-Latency Variant MANTIS
Beierle, Christof; Jean, Jérémy; Kölbl, Stefan
2016-01-01
all known ciphers for ASIC round-based implementations, while still reaching an extremely small area for serial implementations and a very good efficiency for software and micro-controllers implementations (SKINNY has the smallest total number of AND/OR/XOR gates used for encryption process). Secondly...
Fault-based analysis of flexible ciphers
V.I.Korjik
2002-07-01
Full Text Available We consider security of some flexible ciphers against differential fault analysis (DFA. We present a description of the fault-based attack on two kinds of the flexible ciphers. The first kind is represented by the fast software-oriented cipher based on data-dependent subkey selection (DDSS, in which flexibility corresponds to the use of key-dependent operations. The second kind is represented by a DES-like cryptosystem GOST with secrete S-boxes. In general, the use of some secrete operations and procedures contributes to the security of the cryptosystem, however degree of this contribution depends significantly on the structure of the encryption mechanism. It is shown how to attack the DDSS-based flexible cipher using DFA though this cipher is secure against standard variants of the differential and linear cryptanalysis. We also give an outline of ciphers RC5 and GOST showing that they are also insecure against DFA-based attack. We suggest also a modification of the DDSS mechanism and a variant of the advanced DDSS-based flexible cipher that is secure against attacks based on random hardware faults.
Anas Altaleb
2017-03-01
Full Text Available The aim of this work is to synthesize 8*8 substitution boxes (S-boxes for block ciphers. The confusion creating potential of an S-box depends on its construction technique. In the first step, we have applied the algebraic action of the projective general linear group PGL(2,GF(28 on Galois field GF(28. In step 2 we have used the permutations of the symmetric group S256 to construct new kind of S-boxes. To explain the proposed extension scheme, we have given an example and constructed one new S-box. The strength of the extended S-box is computed, and an insight is given to calculate the confusion-creating potency. To analyze the security of the S-box some popular algebraic and statistical attacks are performed as well. The proposed S-box has been analyzed by bit independent criterion, linear approximation probability test, non-linearity test, strict avalanche criterion, differential approximation probability test, and majority logic criterion. A comparison of the proposed S-box with existing S-boxes shows that the analyses of the extended S-box are comparatively better.
Altaleb, Anas; Saeed, Muhammad Sarwar; Hussain, Iqtadar; Aslam, Muhammad
2017-03-01
The aim of this work is to synthesize 8*8 substitution boxes (S-boxes) for block ciphers. The confusion creating potential of an S-box depends on its construction technique. In the first step, we have applied the algebraic action of the projective general linear group PGL(2,GF(28)) on Galois field GF(28). In step 2 we have used the permutations of the symmetric group S256 to construct new kind of S-boxes. To explain the proposed extension scheme, we have given an example and constructed one new S-box. The strength of the extended S-box is computed, and an insight is given to calculate the confusion-creating potency. To analyze the security of the S-box some popular algebraic and statistical attacks are performed as well. The proposed S-box has been analyzed by bit independent criterion, linear approximation probability test, non-linearity test, strict avalanche criterion, differential approximation probability test, and majority logic criterion. A comparison of the proposed S-box with existing S-boxes shows that the analyses of the extended S-box are comparatively better.
V. U.K.. Sastry
2006-01-01
Full Text Available In this paper, we have developed a block cipher by applying an iterative method. In the process of encryption, we have used a key matrix (K in which all the elements are binary bits. In the process of decryption, we have utilized the modular arithmetic inverse (K-1. In the process of encryption, the elements of the plaintext and the elements of the key are thoroughly mixed so that the strength of the algorithm increases remarkably. In this we have obtained the ciphertext for large blocks of plaintext.
Secure transmission of images based on chaotic systems and cipher block chaining
Lakhani, Mahdieh Karimi; Behnam, Hamid; Karimi, Arash
2013-01-01
The ever-growing penetration of communication networks, digital and Internet technologies in our everyday lives has the transmission of text data, as well as multimedia data such as images and videos, possible. Digital images have a vast usage in a number of applications, including medicine and providing security authentication, for example. This applicability becomes evident when images, such as walking or people's facial features, are utilized in their identification. Considering the required security level and the properties of images, different algorithms may be used. After key generation using logistic chaos signals, a scrambling function is utilized for image agitation in both horizontal and vertical axes, and then a block-chaining mode of operation may be applied to encrypt the resultant image. The results demonstrate that using the proposed method drastically degrades the correlation between the image components and also the entropy is increased to an acceptable level. Therefore, the image will become greatly resistant to differential attacks. However, the increasing scrambling rounds and the decreasing number of bits of the blocks result in increasing the entropy and decreasing the correlation.
Cryptanalysis of Some Lightweight Symmetric Ciphers
Abdelraheem, Mohamed Ahmed Awadelkareem Mohamed Ahmed
on a variant of PRESENT with identical round keys. We propose a new attack named the Invariant Subspace Attack that was specifically mounted against the lightweight block cipher PRINTcipher. Furthermore, we mount several attacks on a recently proposed stream cipher called A2U2....
Application of algebraic methods into cryptanalysis of block cipher%代数方法在分组密码分析中的应用
杨璇; 刘金旺
2016-01-01
This paper mainly analyzes algebraic methods that are applied in impossible difference cryptanalysis of block cipher,including linear equations,Boolean algebra,polynomial theory in finite fields and groebner basis theory.Improving the original method of algebra automated search,the improved algorithm can better evaluate the ability of block cipher to resistance impossible differencial cryptanalysis and provide technical support for system safety of the mines.%主要对分组密码的不可能差分分析中所使用到的一些代数方法进行了研究，包括线性方程组的求解、布尔代数、有限域上的多项式理论以及 Groebner 基理论等；对原有的代数自动化搜索方法进行了改进，改进后的算法能更好的评价分组密码抵抗不可能差分分析的能力，为矿山的系统安全提供技术保障。
一类分组密码的S盒重组算法%S-boxes reorganization algorithm for a class of block ciphers
杨宏志; 韩文报
2009-01-01
S盒是许多分组密码唯一的非线性部件,它的密码强度决定了整个密码算法的安全强度.足够大的S盒是安全的,但为了便于实现,分组密码多采用若干小S盒拼凑.针对一类分组密码算法,通过将S盒与密钥相关联,给出了S盒重组算法,丰富了S盒的应用模式,有效提高了分组密码的安全强度.%S-boxes are the only nonlinear components in many block cipher algorithms, and they decide the security strength of the whole algorithm. Generally speaking, a big enough S-box is secure. However, for the convenience of implementation, several small S-boxes were combined. Concerning one class of block ciphers, an S-boxes reorganized algorithm was given, which enriched S-boxes application patterns and improved the security strength.
分组密码算法SM4的低复杂度实现%Low Complexity Implementation of Block Cipher SM4 Algorithm
王晨光; 乔树山; 黑勇
2013-01-01
A basic architecture is proposed for reducing the implementation complexity of SM4 block cipher.The architecture reuses the hardware of encryption/decryption and key expansion module because the encryption/decryption algorithm is very similar with the key expansion algorithm.Optimum trade-off among control-logic complexity,reused-module complexity and throughput is realized through careful analysis and choose of specific realization.A SM4 cipher IP is designed based on this architecture.The designed IP's cost is only 55％ of the traditional design in Field Programmable Gate Array(FPGA).The IP is also synthesized under the SMIC 0.18 μm CMOS process.Its area is 0.079 mm2 with 100 Mb/s throughput.Experimental results of synthesis show that the proposed architecture can reduce the implementation complexity of SM4 block cipher efficiently.%针对分组密码算法SM4中加解密算法与密钥扩展算法的相似性,提出一种将加解密模块与密钥扩展模块复用的基本架构,通过对具体实现结构的分析与选择,使控制逻辑复杂度、复用模块复杂度以及系统吞吐量之间得到权衡.基于该架构设计SM4加解密IP核,在现场可编程门阵列上占用的资源仅为传统设计的55％,基于SMIC 0.18 μm数字CMOS工艺的综合结果显示,仅用0.079 mm2即可实现1 00 Mb/s的数据吞吐量.实验结果表明,该结构可以有效地降低SM4算法的实现复杂度.
Muharrem Tolga Sakallı
2014-01-01
Full Text Available We present an algebraic construction based on state transform matrix (companion matrix for n×n (where n≠2k, k being a positive integer binary matrices with high branch number and low number of fixed points. We also provide examples for 20×20 and 24×24 binary matrices having advantages on implementation issues in lightweight block ciphers and hash functions. The powers of the companion matrix for an irreducible polynomial over GF(2 with degree 5 and 4 are used in finite field Hadamard or circulant manner to construct 20×20 and 24×24 binary matrices, respectively. Moreover, the binary matrices are constructed to have good software and hardware implementation properties. To the best of our knowledge, this is the first study for n×n (where n≠2k, k being a positive integer binary matrices with high branch number and low number of fixed points.
SOSEMANUK: a fast software-oriented stream cipher
Berbain, Come; Canteaut, Anne; Courtois, Nicolas; Gilbert, Henri; Goubin, Louis; Gouget, Aline; Granboulan, Louis; Lauradoux, Cedric; Minier, Marine; Pornin, Thomas; Sibert, Herve
2008-01-01
Sosemanuk is a new synchronous software-oriented stream cipher, corresponding to Profile 1 of the ECRYPT call for stream cipher primitives. Its key length is variable between 128 and 256 bits. It ac- commodates a 128-bit initial value. Any key length is claimed to achieve 128-bit security. The Sosemanuk cipher uses both some basic design principles from the stream cipher SNOW 2.0 and some transformations derived from the block cipher SERPENT. Sosemanuk aims at improv- ing SNOW 2.0 both from the security and from the efficiency points of view. Most notably, it uses a faster IV-setup procedure. It also requires a reduced amount of static data, yielding better performance on several architectures.
Bogdanov, Andrey; Knudsen, L.R.; Leander, Gregor
2012-01-01
This paper considers—for the first time—the concept of key-alternating ciphers in a provable security setting. Key-alternating ciphers can be seen as a generalization of a construction proposed by Even and Mansour in 1991. This construction builds a block cipher PX from an n-bit permutation P and...
Boesgaard, Martin; Vesterager, Mette; Zenner, Erik
2008-01-01
The stream cipher Rabbit was first presented at FSE 2003, and no attacks against it have been published until now. With a measured encryption/decryption speed of 3.7 clock cycles per byte on a Pentium III processor, Rabbit does also provide very high performance. This paper gives a concise...... description of the Rabbit design and some of the cryptanalytic results available....
赵新阳; 郭杰; 周斌
2016-01-01
为了提高数据传输过程的安全性,笔者对国密对称密码算法( SM4 )的多模式实现机制进行研究,分析了模式间的差异和适用场景,统一了多模式编程接口. 宝钢集团有限公司ESB平台与基于云存储技术的网络文件保护系统集成时,采用基于电文密码本( ECB)模式的SM4密码算法实现消息传输的双向加解密,很好地解决了企业系统集成中的信息安全问题.%In order to improve the security of message transmission,the multi encryption modes of the SM4 Block Cipher algorithm are researched, the differences among these encryption modes and the suitable application scenario for each encryption mode are analyzed, and a unified multi-mode pro-gramming interface is provided. When integrating the ESB platform with the TSP system,which is a network file protection system based on the cloud storage technology,in Baosteel Group Corporation, the SM4 Block Cipher algorithm with ECB encryption mode is used to ensure the security of message transmission,which solves the problem of information security in enterprise system integration.
Jensen, Lasse Meinert
to and managing themselves. The question will be if self-monitoring lead to a reduction of complexity, or to a transformation of it into other forms. Current self-tracking practices differ from previous forms of self-interrogation by using quantification to “number” our lives and selves. We cipher ourselves...... in order to make information about our lives and ourselves accessible in another way; as self-tracking advocate Gary Wolf puts it: “Numbers make problems less resonant emotionally but more tractable intellectually”. Tracking personal data promises both emotion-free self-relationships, easy sharing...... and exchanging of data with others, and perhaps most crucially, possibilities for self-experimentation and eventual self-managing. Instead of deciphering one’s life and actions, self-monitoring through numbers ciphers the self in order to manage the complexities of life. Self-tracking practices will provide...
Exclusive-128 Bit NLFSR Stream Cipher for Wireless Sensor Network Applications
K. J. Jegadish Kumar
2013-10-01
Full Text Available A stream cipher is a common method to protect confidential information from unauthorized person. This kind of cryptosystem is preferred to block ciphers because its implementation in hardwareconsumes less power and size. Amidst of different stream ciphers, Non-Linear Feedback Shift Register (NLFSR based one offers the best trade-off between security and hardware capability. This paperdescribes the stream cipher that generates 128 bit keystream using only NLFSR element as its main function and XOR operation. Hence, this cryptosystem is named as Exclusive-128 NLFSR stream cipher.This cipher consists of different sizes of NLFSRs both in Galois and Fibonacci configuration which offers better trade-off between the algorithm security and hardware capability. The essential design principles in developing the stream cipher are adopted from the A5/1 and modified A5/1 stream ciphers. The proposed stream cipher provides promising efficiency in hardware costs in reconfigurable FieldProgrammable Gate Array (FPGA and Application Specific Integrated Circuits (ASIC implementations.
A New Substitution Cipher - Random-X
Falguni Patel
2015-08-01
Full Text Available Ciphers are the encryption methods to prepare the algorithm for encryption and decryption. The currently known ciphers are not strong enough to protect the data. A new substitution cipher Random-X that we introduce in this paper can be used for password encryption and data encryption. Random-X cipher is a unique substitution cipher which replaces the units of plaintext with triplets of letters. The beauty of this cipher is that the encrypted string of the same plain text is not always same. This makes it strong and difficult to crack. This paper covers the principle the implementation ideas and testing of Random-X cipher.
Comment: Comments on "How to repair the Hill cipher"
无
2008-01-01
A modification of the Hill cipher algorithm was recently proposed by Ismail et al.(2006), who claimed that their new scheme could offer more security than the original one due to an extra non-linearity layer introduced via an elaborated key generation mechanism. That mechanism produces one different encryption key for each one of the plaintext blocks. Nevertheless, we show in this paper that their method still has severe security flaws whose weaknesses are essentially the same as that already found in the original Hill cipher scheme.
Jensen, Lasse Meinert
When a person tracks her mood with a smartphone app, is s/he then gathering data about a mental process, engaging in self-cultivation, or managing her conduct with technologies of self-government? This presentation will discuss how self-monitoring afford persons different ways of relating...... in order to make information about our lives and ourselves accessible in another way; as self-tracking advocate Gary Wolf puts it: “Numbers make problems less resonant emotionally but more tractable intellectually”. Tracking personal data promises both emotion-free self-relationships, easy sharing...... and exchanging of data with others, and perhaps most crucially, possibilities for self-experimentation and eventual self-managing. Instead of deciphering one’s life and actions, self-monitoring through numbers ciphers the self in order to manage the complexities of life. Self-tracking practices will provide...
Ekert, Artur; Kay, Alastair; Pope, James
2012-07-28
Alan Turing has certainly contributed to a widespread belief that the quest for a perfect, unbreakable, cipher is a futile pursuit. The ancient art of concealing information has, in the past, been matched by the ingenuity of code-breakers, but no longer! With the advent of quantum cryptography, the hopes of would-be eavesdroppers have been dashed, perhaps for good. Moreover, recent research, building on schemes that were invented decades ago to perform quantum cryptography, shows that secure communication certified by a sufficient violation of a Bell inequality makes a seemingly insane scenario possible-devices of unknown or dubious provenance, even those that are manufactured by our enemies, can be safely used for secure communication, including key distribution. All that is needed to implement this bizarre and powerful form of cryptography is a loophole-free test of a Bell inequality, which is on the cusp of technological feasibility. We provide a brief overview of the intriguing connections between Bell inequalities and cryptography and describe how studies of quantum entanglement and the foundations of quantum theory influence the way we may protect information in the future.
Rabie A. Mahmoud
2016-08-01
Full Text Available To enhance the performance of the KASUMI Metamorphic Cipher, we apply a lightweight Metamorphic Structure. The proposed structure uses four lightweight bit-balanced operations in the function Meta-FO of the KASUMI Metamorphic Cipher. These operations are: XOR, INV, XNOR, and NOP for bitwise XOR, invert, XNOR, and no operation respectively building blocks of the Specialized Crypto Logic Unit (SCLU. In this work, we present a lightweight KASUMI Specialized-Metamorphic Cipher. In addition, we provide a Field Programmable Gate Array (FPGA implementation of the proposed algorithm modification.
A GENERALIZED VERSION OF PLAY FAIR CIPHER
Jitendra Choudhary
2013-06-01
Full Text Available In this paper, we have generalized and modified the play fair cipher. We have introduced confusion and diffusion. The cryptanalysis carried out in this analysis has shown that the proposed play fair cipher is a strong one. The role of cryptography in today’s world is increasing day by day. Information is flowing from are place to another on the network. One most common cryptography technique is substitution cipher. Play fair is most common substitution cipher. In this paper, we present a generalized version of play fair ciphers. Encryption/decryption is a very popular task. We also explain the fundamentals of sequential cryptography.
Quantum enigma cipher as a generalization of the quantum stream cipher
Kato, Kentaro
2016-09-01
Various types of randomizations for the quantum stream cipher by Y00 protocol have been developed so far. In particular, it must be noted that the analysis of immunity against correlation attacks with a new type of randomization by Hirota and Kurosawa prompted a new look at the quantum stream cipher by Y00 protocol (Quant. Inform. Process. 6(2) 2007). From the preceding study on the quantum stream cipher, we recognized that the quantum stream cipher by Y00 protocol would be able to be generalized to a new type of physical cipher that has potential to exceed the Shannon limit by installing additional randomization mechanisms, in accordance with the law of quantum mechanics. We call this new type of physical random cipher the quantum enigma cipher. In this article, we introduce the recent developments for the quantum stream cipher by Y00 protocol and future plans toward the quantum enigma cipher.
DDP-Based Ciphers: Differential Analysis of SPECTR-H64
A.V. Bodrov
2006-01-01
Full Text Available Use of data-dependent (DD permutations (DDP appears to be very efficient while designing fast ciphers suitable for cheap hardware implementation, few papers devoted to security analysis of the DDP-based cryptosystems have been published though. This paper presents results of differential cryptanalysis (DCA of the twelve-round cipher SPECTR-H64 which is one of the first examples of the fast block cryptosystems using DDP as cryptographic primitive. It has been shown that structure of SPECTR-H64 suits well for consideration of the differential characteristics. Experiments have confirmed the theoretic estimations. Performed investigation has shown that SPECTR-H64 is secure against DCA, some elements of this cipher can be improved though. In order to make the hardware implementation faster and cheaper a modified version of this cipher with eight rounds is proposed.
A MAC Mode for Lightweight Block Ciphers
Luykx, Atul; Preneel, Bart; Tischhauser, Elmar Wolfgang;
2016-01-01
, but also allows high-performance parallel implementations. We highlight this in a comprehensive implementation study, instantiating LightMAC with PRESENT and the AES. Moreover, LightMAC allows flexible trade-offs between rate and maximum message length. Unlike PMAC and its many derivatives, Light...
Some security results of the RC4+ stream cipher
Banik, Subhadeep; Jha, Sonu
2015-01-01
The RC4+ stream cipher was proposed as an alternative to the well known RC4 stream cipher. It was claimed by the authors that this new stream cipher was designed to overcome all the weaknesses reported against the alleged RC4 stream cipher. In the design specifications of RC4+, the authors make u...
R. Albrecht, Martin; Rechberger, Christian; Schneider, Thomas
2015-01-01
Designing an efficient cipher was always a delicate balance between linear and non-linear operations. This goes back to the design of DES, and in fact all the way back to the seminal work of Shannon. Here we focus, for the first time, on an extreme corner of the design space and initiate a study...... of symmetric-key primitives that minimize the multiplicative size and depth of their descriptions. This is motivated by recent progress in practical instantiations of secure multi-party computation (MPC), fully homomorphic encryption (FHE), and zero-knowledge proofs (ZK) where linear computations are, compared...... that when encrypting larger amounts of data the new design strategy translates into improvements in computation and communication complexity by up to a factor of 5 compared to AES-128, which incidentally is one of the most competitive classical designs. Furthermore, we identify cases where “free XORs” can...
Implementasi Kombinasi Caesar dan Affine Cipher untuk Keamanan Data Teks
Dian Rachmawati
2015-11-01
Full Text Available Petukaran data yang terjadi secara offline maupunonline sangat rentan dengan ancaman pencurian data. KombinasiCaesar dan Affine Cipher diharapkan mampu untuk menanganiisu keamanan data. Caesar Cipher bekerja denganmemanfaatkan pergeseran atau dikenal dengan shift ciphersementara Affine Cipher bekerja dengan menggunakan kunci duabuah bilangan integer. Kombinasi dua buah algoritma ini mampumengamankan data dan mengembalikan kembali ke bentukaslinya (plainteks, sehingga tidak menyebabkan integritasdatanya hilang. Kata Kunci—plainteks, cipherteks, Caesar cipher, Affinecipher.
Modified Hill Cipher with Key Dependent Permutation and Circular Rotation
V. U.K. Sastry
2007-01-01
Full Text Available In this study, we have modified the Hill cipher, by including a permutation and circular rotation into the cipher. Here both the permutation and the rotation depend upon the key. From the cryptanalysis and the avalanche effect, discussed in this study, we notice that the strength of the cipher is significant.
A Novel Enhancement Technique of the Hill Cipher for Effective Cryptographic Purposes
A. F.A. Abidin
2011-01-01
Full Text Available Problem statement: The Hill cipher is the first polygraph cipher which has a few advantages in data encryption. However, it is vulnerable to known plaintext attack. Besides, an invertible key matrix is needed for decryption. It may become problematic since an invertible key matrix does not always exist. Approach: In this study, a robust Hill algorithm (Hill++ has been proposed. The algorithm is an extension of Affine Hill cipher. A random matrix key, RMK is introduced as an extra key for encryption. An algorithm proposed for involutory key matrix generation is also implemented in the proposed algorithm. Results: A comparative study has been made between the proposed algorithm and the existing algorithms. The encryption quality of the proposed algorithm is also measured by using the maximum deviation factor and correlation coefficient factor. Conclusion/Recommendations: The proposed algorithm introduced a random matrix key which is computed based on the previous ciphertext blocks and a multiplying factor. A modified of Hill Cipher is free from the all-zero plaintext blocks vulnerability. Usage of involutory key for encryption and decryption managed to solve the non invertible key matrix problem. It also simplify the computational complexity in term of generating the inverse key matrix.
Key Recovery Attacks on Recent Authenticated Ciphers
Bogdanov, Andrey; Dobraunig, Christoph; Eichlseder, Maria
2014-01-01
In this paper, we cryptanalyze three authenticated ciphers: AVALANCHE, Calico, and RBS. While the former two are contestants in the ongoing international CAESAR competition for authenticated encryption schemes, the latter has recently been proposed for lightweight applications such as RFID systems...
Coherent pulse position modulation quantum cipher
Sohma, Masaki; Hirota, Osamu [Quantum ICT Research Institute, Tamagawa University, 6-1-1 Tamagawa-gakuen, Machida, Tokyo 194-8610 (Japan)
2014-12-04
On the basis of fundamental idea of Yuen, we present a new type of quantum random cipher, where pulse position modulated signals are encrypted in the picture of quantum Gaussian wave form. We discuss the security of our proposed system with a phase mask encryption.
Differential Fault Attack on KASUMI Cipher Used in GSM Telephony
Zongyue Wang
2014-01-01
Full Text Available The confidentiality of GSM cellular telephony depends on the security of A5 family of cryptosystems. As an algorithm in this family survived from cryptanalysis, A5/3 is based on the block cipher KASUMI. This paper describes a novel differential fault attack on KAUSMI with a 64-bit key. Taking advantage of some mathematical observations on the FL, FO functions, and key schedule, only one 16-bit word fault is required to recover all information of the 64-bit key. The time complexity is only 232 encryptions. We have practically simulated the attack on a PC which takes only a few minutes to recover all the key bits. The simulation also experimentally verifies the correctness and complexity.
A Novel Latin Square Image Cipher
Wu, Yue; Noonan, Joseph P; Agaian, Sos; Chen, C L Philip
2012-01-01
In this paper, we introduce a symmetric-key Latin square image cipher (LSIC) for grayscale and color images. Our contributions to the image encryption community include 1) we develop new Latin square image encryption primitives including Latin Square Whitening, Latin Square S-box and Latin Square P-box ; 2) we provide a new way of integrating probabilistic encryption in image encryption by embedding random noise in the least significant image bit-plane; and 3) we construct LSIC with these Latin square image encryption primitives all on one keyed Latin square in a new loom-like substitution-permutation network. Consequently, the proposed LSIC achieve many desired properties of a secure cipher including a large key space, high key sensitivities, uniformly distributed ciphertext, excellent confusion and diffusion properties, semantically secure, and robustness against channel noise. Theoretical analysis show that the LSIC has good resistance to many attack models including brute-force attacks, ciphertext-only at...
An Enhanced Vigenere Cipher For Data Security
Aized Amin Soofi
2015-08-01
Full Text Available In todays world the amount of data that is exchanged has increased in the last few years so securing the information has become a crucial task. Cryptography is an art of converting plain text message into unreadable message. Encryption algorithms play an important role in information security systems. Encryption is considered as one of the most powerful tool for secure transmission of data over the communication network. Vigenere technique is an example of polyalphabetic stream cipher it has various limitations such as Kasiski and Friedman attack to find the length of encryption key. In this paper an enhanced version of traditional vigenere cipher has been proposed that eliminates the chances of Kaisiski and Friedman attack. Proposed technique also provides better security against cryptanalysis and pattern prediction.
Quantum stream cipher based on optical communications
Hirota, Osamu; Kato, Kentaro; Sohma, Masaki; Usuda, Tsuyoshi S.; HARASAWA, Katsuyoshi
2004-01-01
In 2000, an attractive new quantum cryptography was discovered by H.P.Yuen based on quantum communication theory. It is applicable to direct encryption, for example quantum stream cipher based on Yuen protocol(Y-00), with high speeds and for long distance by sophisticated optical devices which can work under the average photon number per signal light pulse:$ = 1000 \\sim 10000$. In addition, it may provide information-theoretic security against known/chosen plaintext attack, which has no class...
Ciphering Indicator approaches and user awareness
Iosif Androulidakis
2012-12-01
Full Text Available One of the fundamental mobile phone security problems in GSM is the absence of base station authentication, which allows man-in-the-middle attacks. During such attacks, a third party activates a fake base station, which acts as a bypass to the network, thus switching off the encryption and intercepting the user’s communications. 3G mobile networks enforce mutual authentication but this can be circumvented if the 3G band is jammed by the attacker, forcing the phone to connect using GSM. GSM and newer standards provide a user alert indicating that the encryption has been switched off, which is called a Ciphering Indicator. In the present paper, different approaches followed by various manufacturers concerning the Ciphering Indicator are investigated. A total of 38 different mobile phones ranging from old to new and from simple to smart-phones that were produced by 13 different manufacturers were intercepted using a GSM testing device in order to document their reactions. Four approaches were identified with some manufacturers choosing not to implement the feature at all. It was also found that in the cases in which the feature was actually implemented, no universal indication was used and it was seldom documented in the phones’ manuals. User awareness regarding the Ciphering Indicator and security issues was also investigated via an empirical survey employing more than 7,000 users from 10 countries and was found to be significantly low.
Cryptanalysis of the full Spritz stream cipher
Banik, Subhadeep; Isobe, Takanori
2016-01-01
Spritz is a stream cipher proposed by Rivest and Schuldt at the rump session of CRYPTO 2014. It is intended to be a replacement of the popular RC4 stream cipher. In this paper we propose distinguishing attacks on the full Spritz, based on a short-term bias in the first two bytes of a keystream...... and a long-term bias in the first two bytes of every cycle of N keystream bytes, where N is the size of the internal permutation. Our attacks are able to distinguish a keystream of the full Spritz from a random sequence with samples of first two bytes produced by 244.8 multiple key-IV pairs or 260.......8 keystream bytes produced by a single key- IV pair. These biases are also useful in the event of plaintext recovery in a broadcast attack. In the second part of the paper, we look at a state recovery attack on Spritz, in a special situation when the cipher enters a class of weak states. We determine...
Manticore and CS mode : parallelizable encryption with joint cipher-state authentication.
Torgerson, Mark Dolan; Draelos, Timothy John; Schroeppel, Richard Crabtree; Miller, Russell D.; Beaver, Cheryl Lynn; Anderson, William Erik
2004-10-01
We describe a new mode of encryption with inexpensive authentication, which uses information from the internal state of the cipher to provide the authentication. Our algorithms have a number of benefits: (1) the encryption has properties similar to CBC mode, yet the encipherment and authentication can be parallelized and/or pipelined, (2) the authentication overhead is minimal, and (3) the authentication process remains resistant against some IV reuse. We offer a Manticore class of authenticated encryption algorithms based on cryptographic hash functions, which support variable block sizes up to twice the hash output length and variable key lengths. A proof of security is presented for the MTC4 and Pepper algorithms. We then generalize the construction to create the Cipher-State (CS) mode of encryption that uses the internal state of any round-based block cipher as an authenticator. We provide hardware and software performance estimates for all of our constructions and give a concrete example of the CS mode of encryption that uses AES as the encryption primitive and adds a small speed overhead (10-15%) compared to AES alone.
IMPLEMENTASI ENKRIPSI DEKRIPSI ALGORITMA AFFINE CIPHER BERBASIS ANDROID
Sasono Wibowo
2014-11-01
Full Text Available Perkembangan Teknologi Informasi yang cukup pesat khususnya dalam bidang komunikasi menjadikan komunikasi sangat mudah namun dalam implementasinya perlu adanya keamanan tentang informasi yang disampaikan. Dalam komunikasi antar orang pasti memiliki pembicaraan informasi yang bersifat privat atau orang lain tidak boleh tahu tentang pembicaraan yang terjadi. Diperlukannya keamanan untuk menjaga kerahasiaan informasi pada saat komunikasi. Masyarakat lebih sering menggunakan komunikasi dengan telepon seluler karena dinilai mudah dibawa dan tidak repot menggunakannya. Kriptografi yang biasa dikenal sebagai ilmu yang mempelajari bagaimana cara menyembunyikan pesan bisa diterapkan dalam aplikasi pada telepon seluler sebagai contoh smartphone android. Dengan mengimplementasikan algoritma affine cipher maka aplikasi yang akan dibuat bisa mengubah isi pesan yang ada dan dapat mengamankan informasi yang ada. Algoritma affine cipher merupakan perkembangan dari algoritma caesar dimana algoritma affine cipher menggunakan dua kunci. Dengan mengimplementasikan algoritma affine cipher ke dalam android maka diharapkan kita bisa menyimpan informasi dari siapapun tanpa terbaca. Kata Kunci : Kriptografi, Affine Cipher, android, Implementasi, Informasi
Stream cipher based on GSS sequences
HU Yupu; XIAO Guozhen
2004-01-01
Generalized self-shrinking sequences, simply named the GSS sequences,are novel periodic sequences that have many advantages in cryptography. In this paper,we give several results about GSS sequence's application to cryptography. First, we give a simple method for selecting those GSS sequences whose least periods reach the maximum. Second, we give a method for describing and computing the auto-correlation coefficients of GSS sequences. Finally, we point out that some GSS sequences, when used as stream ciphers, have a security weakness.
On the Design of Error-Correcting Ciphers
Mathur Chetan Nanjunda
2006-01-01
Full Text Available Securing transmission over a wireless network is especially challenging, not only because of the inherently insecure nature of the medium, but also because of the highly error-prone nature of the wireless environment. In this paper, we take a joint encryption-error correction approach to ensure secure and robust communication over the wireless link. In particular, we design an error-correcting cipher (called the high diffusion cipher and prove bounds on its error-correcting capacity as well as its security. Towards this end, we propose a new class of error-correcting codes (HD-codes with built-in security features that we use in the diffusion layer of the proposed cipher. We construct an example, 128-bit cipher using the HD-codes, and compare it experimentally with two traditional concatenated systems: (a AES (Rijndael followed by Reed-Solomon codes, (b Rijndael followed by convolutional codes. We show that the HD-cipher is as resistant to linear and differential cryptanalysis as the Rijndael. We also show that any chosen plaintext attack that can be performed on the HD cipher can be transformed into a chosen plaintext attack on the Rijndael cipher. In terms of error correction capacity, the traditional systems using Reed-Solomon codes are comparable to the proposed joint error-correcting cipher and those that use convolutional codes require more data expansion in order to achieve similar error correction as the HD-cipher. The original contributions of this work are (1 design of a new joint error-correction-encryption system, (2 design of a new class of algebraic codes with built-in security criteria, called the high diffusion codes (HD-codes for use in the HD-cipher, (3 mathematical properties of these codes, (4 methods for construction of the codes, (5 bounds on the error-correcting capacity of the HD-cipher, (6 mathematical derivation of the bound on resistance of HD cipher to linear and differential cryptanalysis, (7 experimental comparison
Quantum stream cipher based on optical communications
Hirota, O; Sohma, M; Usuda, T S; Harasawa, K; Hirota, Osamu; Kato, Kentaro; Sohma, Masaki; Usuda, Tsuyoshi S.; Harasawa, Katsuyoshi
2004-01-01
In 2000, an attractive new quantum cryptography was discovered by H.P.Yuen based on quantum communication theory. It is applicable to direct encryption, for example quantum stream cipher based on Yuen protocol(Y-00), with high speeds and for long distance by sophisticated optical devices which can work under the average photon number per signal light pulse:$ = 1000 \\sim 10000$. In addition, it may provide information-theoretic security against known/chosen plaintext attack, which has no classical analogue. That is, one can provide secure communication, even the system has $H(K) << H(X)$. In this paper, first, we give a brief review on the general logic of Yuen's theory. Then, we show concrete security analysis of quantum stream cipher to quantum individual measurement attacks. Especially by showing the analysis of Lo-Ko known plaintext attack, the feature of Y-00 is clarified. In addition, we give a simple experimental result on the advantage distillation by scheme consisting of intensity modulation/dir...
A chaotic cipher Mmohocc and its security analysis
Zhang, Xiaowen; Shu, Li; Tang, Ke
2007-04-01
In this paper we introduce a new chaotic stream cipher Mmohocc which utilizes the fundamental chaos characteristics. The designs of the major components of the cipher are given. Its cryptographic properties of period, auto- and cross-correlations, and the mixture of Markov processes and spatiotemporal effects are investigated. The cipher is resistant to the related-key-IV, Time/Memory/Data tradeoff, algebraic, and chosen-text attacks. The keystreams successfully passed two batteries of statistical tests and the encryption speed is comparable with RC4.
From Greeks to Today: Cipher Trees and Computer Cryptography.
Grady, M. Tim; Brumbaugh, Doug
1988-01-01
Explores the use of computers for teaching mathematical models of transposition ciphers. Illustrates the ideas, includes activities and extensions, provides a mathematical model and includes computer programs to implement these topics. (MVL)
Secure and Efficient Pseudorandom Bit Generator for Chaotic Stream Ciphers
WANG Xiao-Min; ZHANG Jia-Shu
2007-01-01
Based on the entropy criterion and n-dimensional uniform distribution of nonlinear digital filter (NDF), we present an efficient NDF-based pseudorandom bit generator (NDF-PRBG) for chaotic stream ciphers. The cryptographic properties of the proposed NDF-PRBG are analysed, and some experiments are made. The results show that it has desirable cryptographic properties, and can be used to construct secure stream ciphers with high speed.
New Design of Crypto-Based Pseudo random number generator (CBPRNG using BLOW FISH cipher
T.Chalama Reddy
2013-06-01
Full Text Available Random Number Generators (RNGs are an important building block for algorithms and protocols in cryptography. Random number generation is used in a wide variety of cryptographic operations, such as key generation and challenge/response protocols. A random number generator outputs a sequence of 0s and 1s such that at any position, the next bit cannot be expected on the previous bits. However, true random number produces non- deterministic output since if the same random generator is run twice, identical results are not received. Thus we go for pseudo random number generator that is deterministic device because if this random number generator is run twice or more, it gives same results. Our paper presents new crypto based pseudorandom number generator. It uses BLOW FISH ciphers and the Cipher-Block chaining (CBC mode that uses three stages of the block chaining. The plain text for each stage comes from the output of the first BLOW FISH, which uses the 64-Bit date and time as the plain text. CBPRNG creates three 64-bit random numbers, the first and the second are concatenated to create a 128-random number and the third is used as next initial vector (IV for CBPRNG. Our Crypto-Based Pseudo-random Number Generator produces a sequence of bits that has arandom looking distribution. This new generator helps to develop huge range cryptographic applications to increase the system security. A number of applications such as financial security applications and Pretty Good Privacy (PGP use this technique.
Cipher for smart card using Unicode, length and position
Natang. A. Salgia
2011-12-01
Full Text Available Smart cards have become a common thing today. Smart cards with various utilities are used today since they are easy to carry and relatively secured. But due to advancement of technologies, smart cards are becoming increasingly insecure. A paper from certain conference suggested a new encryption algorithm to keep the information secured in smart cards and to overcome forgery attacks. It claims that, on an average, even a supercomputer will take 101084 years to decrypt, which is much higher than the previous proposals. It makes use of the length of the PIN, and the position and the Unicode value of every character in the PIN along with a secret key to create cipher text. Also, final cipher text is formed by combining two different cipher texts, one from date and time and another from PIN and secret key. And only this final cipher text is saved on the smart card making this algorithm further more secured. But few anomalies were noticed in it. Firstly, the cipher text generated using proposed formula for encryption makes securing it using position problematic. Secondly, the formula given in actual paper misses an important step, without which decryption process gives wrong output. With proposed changes these problems are eradicated and the algorithm becomes more difficult to hack.
Improved Feistel-based ciphers for wireless sensor network security
Tamara PAZYNYUK; Jian-zhong LI; George S.OREKU
2008-01-01
Wireless sensor networks (WSNs) are exposed to a variety of attacks.The quality and complexity of attacks are rising day by day.The proposed work aims at showing how the complexity of modem attacks is growing accordingly,leading to a similar rise in methods of resistance.Limitations in computational and battery power in sensor nodes are constraints on the diversity of security mechanisms.We must apply only suitable mechanisms to WSN where our approach was motivated by the application of an improved Feistel scheme.The modified accelerated-cipher design uses data-dependent permutations,and can be used for fast hardware,firmware,software and WSN encryption systems.The approach presented showed that ciphers using this approach are less likely to suffer intrusion of differential cryptanalysis than currently used popular WSN ciphers like DES,Camellia and so on
Why IV Setup for Stream Ciphers is Difficult
Zenner, Erik
2007-01-01
In recent years, the initialization vector (IV) setup has proven to be the most vulnerable point when designing secure stream ciphers. In this paper, we take a look at possible reasons why this is the case, identifying numerous open research problems in cryptography.......In recent years, the initialization vector (IV) setup has proven to be the most vulnerable point when designing secure stream ciphers. In this paper, we take a look at possible reasons why this is the case, identifying numerous open research problems in cryptography....
Reduction of Key Search Space of Vigenere Cipher Using Particle Swarm Optimization
Ganapathi Sivagurunathan
2011-01-01
Full Text Available Problem statement: With the demand for effective network security is increasing, it becomes necessary to find the strength and weaknesses of the existing cryptographic methods. Vigenere cipher, a classical cipher is analyzed for its strength against a cipher only attack. Approach: The cipher texts so selected were of various sizes up to 1 Kb. A biologically inspired algorithm, Particle Swarm Optimization (PSO was applied to the problem of crypt analyzing the Vigenere cipher. PSO was an optimization technique and its used on the problem of optimizing the fitness function designed for Vigenere cipher was performed. Results: It was seen that PSO is able to find the keyword employed and the other possible combinations for the keyword. Conclusion: PSO is better than genetic algorithm to solve Vigenere cipher and can be used to find the keyword with lesser size.
A FRAMEWORK FOR REAL-VALUED CIPHER SYSTEMS
Zhaozhi ZHANG; Nan JIANG
2007-01-01
Most cipher systems designed thus far are binary-valued or integer-valued cipher systems.Their security relies on the assumption that one-way functions exist. Though the existence of one-way functions has not been proved yet, most cryptographic researchers believe that one-way functions exist.In addition, many candidates for one-way functions have been proposed. Therefore, the key step for developing real-valued cipher systems is to define real one-way functions and to propose candidates for them. In this paper, based on computational complexity theory over the real field, we give two definitions of real one-way functions; one is for digital one-way functions and the other is for general one-way functions. Candidates for these two classes of one-way functions are also proposed. Moreover,we present two examples to demonstrate that the candidates for both digital one-way functions and general one-way functions can be applied to construct secure real-valued cipher systems.
Escaping Embarrassment: Face-Work in the Rap Cipher
Lee, Jooyoung
2009-01-01
How do individuals escape embarrassing moments in interaction? Drawing from ethnographic fieldwork, in-depth interviews, and video recordings of weekly street corner ciphers (impromptu rap sessions), this paper expands Goffman's theory of defensive and protective face-work. The findings reveal formulaic and indirect dimensions of face-work. First,…
Escaping Embarrassment: Face-Work in the Rap Cipher
Lee, Jooyoung
2009-01-01
How do individuals escape embarrassing moments in interaction? Drawing from ethnographic fieldwork, in-depth interviews, and video recordings of weekly street corner ciphers (impromptu rap sessions), this paper expands Goffman's theory of defensive and protective face-work. The findings reveal formulaic and indirect dimensions of face-work. First,…
Substitution-diffusion based Image Cipher
Narendra K Pareek
2011-03-01
Full Text Available In this paper, a new image encryption scheme using a secret key of 128-bit size is proposed. In thealgorithm, image is partitioned into several key based dynamic blocks and further, each block passesthrough the eight rounds of diffusion as well as substitution process. In diffusion process, sequences ofblock pixels are rearranged within the block by a zigzag approach whereas block pixels are replaced withanother by using difference calculation of row and column in substitution process. Due to high order ofsubstitution and diffusion, common attacks like linear and differential cryptanalysis are infeasible. Theexperimental results show that the proposed technique is efficient and has high security features.
Cipher quasi-chaotic code for frequency hopping communications
王宏霞; 何晨; 虞厥邦
2004-01-01
The chaotic frequency hopping (FH) communication systems have been presented so far. The chaotic sequences possesses good randomness and sensitive dependence on initial conditions, which is quite advantageous to run the FH codes in code-division multiple access (CDMA) systems. But the finite precision of computation and the fact of the low-dimensional chaos predicted easily cause difficulty in chaotic application. In this paper, some disadvantages associated with the conventional FH codes and the chaotic code scrambled by m-sequences are reviewed briefly. In order to overcome these drawbacks to some extents, a new higher performance FH code called cipher quasi-chaotic (CQC) code is proposed,which is generated by combining the clock-controlled stream cipher technique and chaotic dynamics. Performance analysis applying in FH communication systems of this kind of code is given. The privacy of the CQC sequence is also analyzed.
A Study on the Stream Cipher Embedded Magic Square of Random Access Files
Liu, Chenglian; Zhao, Jian-Ming; Rafsanjani, Marjan Kuchaki; Shen, Yijuan
2011-09-01
Magic square and stream cipher issues are both interesting and well-tried topics. In this paper, we are proposing a new scheme which streams cipher applications for random access files based on the magic square method. There are two thresholds required to secure our data, if using only decrypts by the stream cipher. It isn't to recovery original source. On other hand, we improve the model of cipher stream to strengthen and defend efficiently; it also was its own high speed and calculates to most parts of the key stream generator.
The Shannon Cipher System with a Guessing Wiretapper: General Sources
Hanawal, Manjesh Kumar
2010-01-01
The Shannon cipher system is studied in the context of general sources using a notion of computational secrecy introduced by Merhav & Arikan. Bounds are derived on limiting exponents of guessing moments for general sources. The bounds are shown to be tight for iid, Markov, and unifilar sources, thus recovering some known results. A close relationship between error exponents and correct decoding exponents for fixed rate source compression on the one hand and exponents for guessing moments on the other hand is established.
Pemecahan Sandi Kriptografi dengan Menggabungkan Metode Hill Cipher dan Metode Caesar Chipher
Indria Eka Wardani
2015-05-01
Full Text Available Message is a privacy statement which is made by a person and addressed to another person with the consent of people who have made the message. But with the development of modern technology resulted in a high level of privacy for their safety message. Especially lately act haeker (security breaker are increasingly rampant and alarming message makers. To address this, the authors will examine and discuss the cryptographic cipher to convey a secret message privacy. Message in the form of a password using cryptography in this paper Combining of Hill Cipher Method and Caesar Cipher Methods.In the operation process of encryption and decryption passwords cryptography, the steps using the Caesar CipherMethods, whereas in steps using keys by using Hill Cipher method. In the making and the first decoding the message makers and recipients know how the operation technique. Thus the expected delivery of message privacy secured.
An Effective and Secure Cipher Based on SDDO
Bac Do Thi
2012-10-01
Full Text Available To improve the efficiency of security of the information secure mechanism, an algorithm BMD-128 is proposed. This algorithm is built on the SDDO. Using this operator decreases significanthy the cost of hardware implementation. Besides, it also ensures both the high applicability in the transaction needing the change of session keys with high frequency and the ability against slide attack. Concurrently, this algorithm also eliminates the weak keys without the complex round key proceduce. The algorithm is evaluated regards to the standard NESSIE and the ability against the differential cryptanalysis. Concurrently, it is also compared the performance with the other famous ciphers when implementing on hardware FPGA.
A quantum symmetric key cipher(Y-00) and key generation (Quantum stream cipher-Part II)
Hirota, O; Sohma, M; Fuse, M; Hirota, Osamu; Kato, Kentaro; Sohma, Masaki; Fuse, Masaru
2004-01-01
What obstructs the realization of useful quantum cryptography is single photon scheme, or entanglement which is not applicable to the current infrastructure of optical communication network. We are concerned with the following question: Can we realize the information theoretically secure symmetric key cipher under "the finite secret key" based on quantum-optical communications? A role of quantum information theory is to give an answer for such a question. As an answer for the question, a new quantum cryptography was proposed by H.P.Yuen, which can realize a secure symmetric key cipher with high speeds(Gbps) and for long distance(1000 Km). Although some researchers claim that Yuen protocol(Y-00) is equivalent to the classical cryptography, they are all mistaken. Indeed it has no classical analogue, and also provides a generalization even in the conventional cryptography. At present, it is proved that a basic model of Y-00 has at least the security such as $H(X|Y_E)=H(K|Y_E)=H(K)$, $H(K|Y_E,X)\\sim 0$ under the ...
K. Anup Kumar
2012-07-01
Full Text Available In this investigation, we have modified the Feistel cipher by taking the plaintext in the form of a pair of square matrices. Here we have introduced the operation multiplication with the key matrices and the modular arithmetic addition in encryption. The modular arithmetic inverse of the key matrix is introduced in decryption. The cryptanalysis carried out in this paper clearly indicate that this cipher cannot be broken by the brute force attack and the known plaintext attack.
Jaber Hosseinzadeh
2016-07-01
Full Text Available Low-resource devices like wireless sensor networks have some limitations on memory, power and energy. Using common encryption algorithms are not appropriate for these devices due to their hard limitations and leads to a waste of energy and power. Here, lightweight symmetric ciphers have been evaluated in hardware and software implementations. Comprehensive Evaluation of lightweight ciphers in this work is performed based on cost, speed, efficiency and balance criterion. In each of the criteria, evaluation is done based on a specific measure and the best ciphers have been introduced in each. Evaluation in terms of hardware and software implementation indicates the superiority of SPECK and SIMON ciphers. Evaluation in terms of speed in hardware implementation indicates the superiority of Trivium and Grain, and it shows the superiority of MASHA and SPECK in software implementation. Results of the Evaluation in terms of efficiency express the superiority of SIMON and SPECK. The results of these evaluations helps finding ciphers appropriate to the user based on requirements and restrictions. The user sets his desired system and then obtains the system needs; at the final step, based on the type of requirements, the results of our work help the system to select the appropriate cipher.
Schrödinger's code-script: not a genetic cipher but a code of development.
Walsby, A E; Hodge, M J S
2017-06-01
In his book What is Life? Erwin Schrödinger coined the term 'code-script', thought by some to be the first published suggestion of a hereditary code and perhaps a forerunner of the genetic code. The etymology of 'code' suggests three meanings relevant to 'code-script which we distinguish as 'cipher-code', 'word-code' and 'rule-code'. Cipher-codes and word-codes entail translation of one set of characters into another. The genetic code comprises not one but two cipher-codes: the first is the DNA 'base-pairing cipher'; the second is the 'nucleotide-amino-acid cipher', which involves the translation of DNA base sequences into amino-acid sequences. We suggest that Schrödinger's code-script is a form of 'rule-code', a set of rules that, like the 'highway code' or 'penal code', requires no translation of a message. Schrödinger first relates his code-script to chromosomal genes made of protein. Ignorant of its properties, however, he later abandons 'protein' and adopts in its place a hypothetical, isomeric 'aperiodic solid' whose atoms he imagines rearranged in countless different conformations, which together are responsible for the patterns of ontogenetic development. In an attempt to explain the large number of combinations required, Schrödinger referred to the Morse code (a cipher) but in doing so unwittingly misled readers into believing that he intended a cipher-code resembling the genetic code. We argue that the modern equivalent of Schrödinger's code-script is a rule-code of organismal development based largely on the synthesis, folding, properties and interactions of numerous proteins, each performing a specific task. Copyright © 2016. Published by Elsevier Ltd.
Hill Cipher and Least Significant Bit for Image Messaging Security
Muhammad Husnul Arif
2016-02-01
Full Text Available Exchange of information through cyberspace has many benefits as an example fast estimated time, unlimited physical distance and space limits, etc. But in these activities can also pose a security risk for confidential information. It is necessary for the safety that can be used to protect data transmitted through the Internet. Encryption algorithm that used to encrypt message to be sent (plaintext into messages that have been randomized (ciphertext is cryptography and steganography algorithms. In application of cryptographic techniques that will be used is Hill Cipher. The technique is combined with steganography techniques Least Significant Bit. The result of merging techniques can maintain the confidentiality of messages because people who do not know the secret key used will be difficult to get the message contained in the stego-image and the image that has been inserted can not be used as a cover image. Message successfully inserted and extracted back on all samples with a good image formats * .bmp, * .png , * .jpg at a resolution of 512 x 512 pixels , 256 x 256 pixels. MSE and PSNR results are not influenced file format or file size, but influenced by dimensions of image. The larger dimensions of the image, then the smaller MSE that means error of image gets smaller.
Fast correlation attack on stream cipher ABC v3
ZHANG HaiNa; LI Lin; WANG XiaoYun
2008-01-01
ABC v3 is a stream cipher submitted to the ECRYPT eStream project and has entered the second evaluation phase.Its key length is 128 bits.In this paper,we find large numbers of new weak keys of ABC family and introduce a method to search for them,and then apply a fast correlation attack to break ABC v3 with weak keys.We show that there are at least 2103.71 new weak keys in ABC v3.Recovering the internal state of a weak key requires 236.05 keystream words and 250.56 operations.The attack can be applied to ABC v1 and v2 with the same complexity as that of ABC v3.However,the number of weak keys of ABC v1 as well as ABC v2 decreases to 297+295.19.It reveals that ABC v3 incurs more weak keys than that of ABC v1 and v2.
A MULTICORE COMPUTER SYSTEM FOR DESIGN OF STREAM CIPHERS BASED ON RANDOM FEEDBACK
Borislav BEDZHEV
2013-01-01
Full Text Available The stream ciphers are an important tool for providing information security in the present communication and computer networks. Due to this reason our paper describes a multicore computer system for design of stream ciphers based on the so - named random feedback shift registers (RFSRs. The interest to this theme is inspired by the following facts. First, the RFSRs are a relatively new type of stream ciphers which demonstrate a significant enhancement of the crypto - resistance in a comparison with the classical stream ciphers. Second, the studding of the features of the RFSRs is in very initial stage. Third, the theory of the RFSRs seems to be very hard, which leads to the necessity RFSRs to be explored mainly by the means of computer models. The paper is organized as follows. First, the basics of the RFSRs are recalled. After that, our multicore computer system for design of stream ciphers based on RFSRs is presented. Finally, the advantages and possible areas of application of the computer system are discussed.
Penerapan CIELab dan Chaos sebagai Cipher pada Aplikasi Kriptografi Citra Digital
Linna Oktaviana Sari
2013-04-01
Full Text Available The development of Internet supports people to transmit information, such as text, images and other media quickly. However, digital images transmitted over the Internet are very vulnerable to attacks, for examples modification and duplication by unauthorized people. Therefore, cryptography as one of method for data security has been developed. This research proposed a combination of color structure CIELab and key randomization by logistic map from chaos as new cipher in digital image cryptographic applications. Cipher is applied to the encryption and decryption process. Implementation of new cipher in cryptographic digital images application was built with Matlab R2010a. Based on the research that has been done, it was found that combination CIELab and chaos can be applied as a new cipher on the encryption and decryption of digital images for cryptographic applications with processing time less than 1 second. Under possible maximum key range on RGB image by 5,2x 1033, the cipher was sufficiently secure against brute-force attack. Decrypted image has good quality with PSNR greater than 50 dB for digital image formatted in “tiff” and “png”.
DSP-128:Stream Cipher Based On Discrete Log Problem And Polynomial Arithmetic
M. K. Suwais
2008-01-01
Full Text Available DSP-128 is a new multithreaded stream cipher based on the intractability of the Discrete Logarithm Problem (DLP with key size of 128-bit. The design of DSP-128 is divided into three stages: Initialization Stage, Keystream Generation Stage, and Encryption Stage. The design goal of DSP-128 is to come up with a secure stream cipher with good performance for data encryption. The experimental results show that the encryption rate of DSP-128 is one time slower (running on single processor than the widely adapted stream cipher RC4, with a higher level of security against possible cryptanalysis attacks. However, because of its multithreaded nature, DSP-128 can take the speed up advantage of multi-core processor architectures which are available widely.
Kato, Kentaro; Hirota, Osamu
2011-08-01
The quantum noise based direct encryption protocol Y-OO is expected to provide physical complexity based security, which is thought to be comparable to information theoretic security in mathematical cryptography, for the. physical layer of fiber-optic communication systems. So far, several randomization techniques for the quantum stream cipher by Y-OO protocol have been proposed, but most of them were developed under the assumption that phase shift keying is used as the modulation format. On the other hand, the recent progress in the experimental study on the intensity modulation based quantum stream cipher by Y-OO protocol raises expectations for its realization. The purpose of this paper is to present design and implementation methods of a composite model of the intensity modulation based quantum stream cipher with some randomization techniques. As a result this paper gives a viewpoint of how the Y-OO cryptosystem is miniaturized.
Exploiting SIMD Instructions in Modern Microprocessors to Optimize the Performance of Stream Ciphers
P. Mabin Joseph
2013-05-01
Full Text Available Modern microprocessors are loaded with a lot of performance optimization features. Single Instruction Multiple Data (SIMD instruction set feature specially designed for improving the performance of multimedia applications is one among them. But most of the encryption algorithms do not use these features to its fullest. This paper discusses various optimization principles to be followed by encryption algorithm designers to exploit the features of underlying processor to the maximum. It also analyses the performance of four eSTREAM finalist stream ciphers – HC-128, Rabbit, Salsa 20/12 and Sosemanuk – under various methods of implementation. Scope of implementing these stream ciphers using SIMD instructions is examined and improvement in performance achieved by this implementation has been measured. Modifications in the algorithm which provide further improvement in performance of these ciphers are also studied.
Hardware stream cipher with controllable chaos generator for colour image encryption
Barakat, Mohamed L.
2014-01-01
This study presents hardware realisation of chaos-based stream cipher utilised for image encryption applications. A third-order chaotic system with signum non-linearity is implemented and a new post processing technique is proposed to eliminate the bias from the original chaotic sequence. The proposed stream cipher utilises the processed chaotic output to mask and diffuse input pixels through several stages of XORing and bit permutations. The performance of the cipher is tested with several input images and compared with previously reported systems showing superior security and higher hardware efficiency. The system is experimentally verified on XilinxVirtex 4 field programmable gate array (FPGA) achieving small area utilisation and a throughput of 3.62 Gb/s. © The Institution of Engineering and Technology 2013.
Cryptanalysis of PRESENT-like ciphers with secret S-boxes
Borghoff, Julia; Knudsen, Lars Ramkilde; Leander, Gregor;
2011-01-01
At Eurocrypt 2001, Biryukov and Shamir investigated the security of AES-like ciphers where the substitutions and affine transformations are all key-dependent and successfully cryptanalysed two and a half rounds. This paper considers PRESENT-like ciphers in a similar manner. We focus on the settings......, we outline how our attack strategy can be applied to an extreme case where the S-boxes are chosen uniformly at random for each round and where the bit permutation is secret as well. © 2011 Springer-Verlag....
A Synchronous Stream Cipher Generator Based on Quadratic Fields (SSCQF
Younes ASIMI
2015-12-01
Full Text Available In this paper, we propose a new synchronous stream cipher called SSCQF whose secret-key is Ks=(z1,...zn where zi is a positive integer. Let d1, d2,..., dN be N positive integers in {0,1,...2m -1} such that di=zi mod2m with m and m>=8. Our purpose is to combine a linear feedback shift registers LFSRs, the arithmetic of quadratic fields: more precisely the unit group of quadratic fields, and Boolean functions [14]. Encryption and decryption are done by XRO`ing the output pseudorandom number generator with the plaintext and ciphertext respectively. The basic ingredients of this proposal stream generator SSCQF rely on the three following processes: In process I , we constructed the initial vectors IV={X1,...,Xn} from the secret-key Ks=(z1,...zn by using the fundamental unit of Q( Nvdi if di is a square free integer otherwise by splitting di, and in process II, we regenerate, from the vectors Xi, the vectors Yi having the same length L, that is divisible by 8 (equations (2 and (3 . In process III , for each Yi , we assign L/8 linear feedback shift registers, each of length eight. We then obtain N x L/8 linear feedback shift registers that are initialized by the binary sequence regenerated by process II , filtered by primitive polynomials, and the combine the binary sequence output with L/8 Boolean functions. The keystream generator, denoted K , is a concatenation of the output binary sequences of all Boolean functions.
Fides: Lightweight Authenticated Cipher with Side-Channel Resistance for Constrained Hardware
Bilgin, Begül; Bogdanov, Andrey; Knezevic, Miroslav; Mendel, Florian; Wang, Qingju; Bertoni, G.; Coron, J.S.
2013-01-01
In this paper, we present a novel lightweight authenticated cipher optimized for hardware implementations called Fides. It is an online nonce-based authenticated encryption scheme with authenticated data whose area requirements are as low as 793 GE and 1001 GE for 80-bit and 96-bit security, respect
Ciphering the Unnamable through the Letter: Horror in the Poetry of Paul Celan
David Jiménez Arenas
2014-10-01
Full Text Available The purpose of this text is to addressthe intersection between horrorand war and its expression in thework of Paul Celan. It examinesone of these manifestations, silence,from the perspective of psychoanalysisand then goes on to discussthe ways in which silence occursin poetry. The conclusion is thatsilence arises due to the impossibilityof ciphering horror by resortingto the letter.
A Hill Cipher Modification Based on Eigenvalues Extension with Dynamic Key Size HCM-EXDKS
Ahmed Y. Mahmoud
2014-04-01
Full Text Available All the proposed Hill cipher modifications have been restricted to the use of dynamic keys only. In this paper, we propose an extension of Hill cipher modification based on eigenvalues HCM-EE, called HCM-EXDKS. The proposed extension generating dynamic encryption key matrix by exponentiation that is made efficiently with the help of eigenvalues, HCM-EXDKS introduces a new class of dynamic keys together with dynamically changing key size. Security of HCM-EXDKS is provided by the use of a large number of dynamic keys with variable size. The proposed extension is more effective in the encryption quality of RGB images than HCM-EE and Hill cipher-known modifications in the case of images with large single colour areas and slightly more effective otherwise. HCM-EXDKS almost has the same encryption time as HCM-EE, and HCM-HMAC. HCM-EXDKS is two times faster than HCM-H, having the best encryption quality among Hill cipher modifications compared versus HCM-EXDKS.
Gbits/s physical-layer stream ciphers based on chaotic light
Zhao, Qingchun
2010-01-01
We propose a novel high-speed stream cipher encryption scheme based on the true random key generated by a chaotic semiconductor laser. A 5-Gbits/s non-return-to-zero plaintext is successfully encrypted and decrypted using this cryptography. The scheme can be applied in the areas of real-time high-speed physical encryption.
Blondeau, Celine; Bogdanov, Andrey; Wang, Meiqin
2014-01-01
significant.At EUROCRYPT'13, a link between these two distinguishers has been presented. However, though being independent of the underling structure of the cipher, it is usually not useful for most known ID or ZC distinguishers. So despite the relevance of those attacks, the question of their equivalence...... or inequivalence has not been formally addressed so far in a constructive practical way.In this paper, we aim to bridge this gap in the understanding of the links between the ID and ZC properties. We tackle this problem at the example of two wide classes of ciphers, namely, Feistel- and Skipjack-type ciphers...
Andro Alif Rakhman
2015-07-01
Full Text Available Penggunaan informasi melalui media gambar atau citra mempunyai beberapa kelemahan, salah satunya adalah kemudahan melakukan manipulasi citra oleh pihak-pihak tertentu dengan bantuan teknologi yang berkembang sekarang ini. Upaya dalam peningkatan pengamanan pengiriman informasi melalui media gambar dan perlindungan atas hak cipta hasil karya media digital maka algoritma kriptografi dapat diterapkan untuk pengamanan citra tersebut. Pada penelitian ini, menggunakan perpaduan algoritma Rivest Shamir Adleman (RSA dan Vigenere Cipher untuk melakukan pengamanan citra. Citra yang akan digunakan yaitu file bitmap dengan kedalaman piksel 8 bit. Citra akan diolah dengan cara mengenkripsi nilai indeks warna RGB pada masing-masing piksel dengan menggunakan algoritma kriptografi RSA terlebih dahulu kemudian dilanjutkan dengan menggunakan algoritma Vigenere Cipher. Sedangkan untuk tahap pendekripsiannya dilakukan dengan menggunakan algoritma Vigenere Cipher terlebuh dahulu kemudian menggunakan algoritma kriptografi RSA. Selanjutnya dilakukan analisis pengaruh penerapan algoritma Rivest Shamir Adleman (RSA dan Vigenere Cipher pada citra yang akan diamankan, meliputi analisis ruang kunci, analisis perubahan indeks warna, dan analisis waktu proses enkripsi dan deskripsi.Pengujian yang dilakukan untuk analisis tersebut, menggunakan citra berdimensi 3840 x 2160 piksel dan ukuran file 7,91 MB dan citra berdimensi 5012 x 2819 piksel dan ukuran file 13,4 MB. Analisis ruang kunci menunjukkan bahwa citra telah berhasil didekripsikan dan secara visual pola citra kembali ke bentuk semula tanpa mengalami cacat sedikitpun. Analisis perubahan indek warna, dilihat secara visual pada hasil palette warna membuktikan bahwa metode enkripsi yang dirancang telah berhasil digunakan untuk memperbaruhi nilai indeks warna citra asli. Sedangkan dari analisis waktu proses enkripsi dan deskripsi dapat disimpulkan Rata-rata lama waktu yang dibutuhkan untuk proses dekripsi lebih lama
An All-In-One Approach to Differential Cryptanalysis for Small Block Ciphers
Albrecht, Martin Roland; Leander, Gregor
2012-01-01
We present a framework that unifies several standard differential techniques. This unified view allows us to consider many, potentially all, output differences for a given input difference and to combine the information derived from them in an optimal way. We then propose a new attack that implic...
A Cryptosystem Based on Hilbert Matrix using Cipher Block Chaining Mode
Raja, Penmetsa V Krishna; Avadhani, P S
2011-01-01
Cryptography is the science of using mathematics to encrypt and decrypt data. Cryptography enables you to store sensitive information or transmit it across insecure networks so that it cannot be read by anyone except the intended recipient. While cryptography is the science of securing data, cryptanalysis is the science of analyzing and breaking secure communication. Classical cryptanalysis involves an interesting combination of analytical reasoning, application of mathematical tools and pattern finding. The objectives of the proposed work are to propose a new cryptographic method based on the special matrix called the Hilbert matrix for authentication and confidentiality and to propose a model for confidentiality and authentication using a combination of symmetric and public cryptosystems. Further, it is extended to shared key cryptosystems with the concept of digital enveloping using a session key. In the present work an algorithm for shared key encryption is developed using Hilbert matrix cryptosystem. In ...
Bannier, Arnaud; Filiol, Eric
2017-01-01
Recent years have shown that more than ever governments and intelligence agencies try to control and bypass the cryptographic means used for the protection of data. Backdooring encryption algorithms is considered as the best way to enforce cryptographic control. Until now, only implementation backdoors (at the protocol/implementation/management level) are generally considered. In this paper we propose to address the most critical issue of backdoors: mathematical backdoors or by-design backdoo...
Exponential Brute-Force Complexity of A Permutation Based Stream Cipher
Mohammed Omari
2013-01-01
Full Text Available This paper introduces a permutation generation mechanism based on a shared secret key. The generated permutation vectors are used as encryption keys in a stream ciphering cryptosystem. We investigated various types of attacks on the known stream cipher RC4 and patched most of its loopholes, especially biased-byte and state-related attacks. Unique to our approach, we prove mathematically that the complexity of brute-forcing such a system is (2n, where n is the key size in bytes. This paper also presents a complete security model using permutation-based encryption, in order to handle privacy. In addition, our approach achieved higher performance than that of existing peer techniques, while maintaining solid security. Experimental results show that our system is much faster than the existing security mechanisms, such as AES and DES.
Theoretical design for a class of chaotic stream cipher based on nonlinear coupled feedback
Hu Guojie; Wang Lin; Feng Zhengjin
2005-01-01
A class of chaotic map called piecewise-quadratic-equation map to design feedback stream cipher is proposed.Such map can generate chaotic signals that have uniform distribution function, δ-like autocorrelation function. Compared with the piecewise-linear map, this map provides enhanced security in that they can maintain the original perfect statistical properties, as well as overcome the defect of piecewise-linearity and expand the key space. This paper presents a scheme to improve the local complexity of the chaotic stream cipher based on the piecewise-quadratic-equationmap.Both the theoretic analysis and the results of simulation show that this scheme improves the microstructure of the phasespace graph on condition that the good properties of the original scheme are remained.
Solving for the RC4 stream cipher state register using a genetic algorithm
Benjamin Ferriman
2014-06-01
Full Text Available The RC4 stream cipher has shown to be quite resilient to cryptanalysis for the 26 years it has been around. The algorithm is still one of the most widely used methods of encryption over the Internet today being implemented through the Secure Socket Layer and Transport Layer Security protocols. Genetic algorithms are a sub-class of evolutionary algorithms that have been used to help solve many different problems of optimization in a variety of disciplines. In this paper we will examine the abilities of the genetic algorithm as a tool to help solve the permutation that is stored as the state register of the RC4 stream cipher. Finally, we will show that on average the genetic algorithm can solve 100% of the keystream in 2121:5 generations.
Futami, Fumio; Hirota, Osamu
2014-09-01
Wireless communication of aviation contains high capacity confidential information and therefore such communication requires secure high speed data communication scheme by using reliable cipher. In this report, the authors propose free space optical communication by utilizing optical intensity-modulated Y-00 cipher for applications of secure aviation systems including unmanned aircraft systems. Y-00 cipher transmitter and receiver with intensity levels of 4096 at data rate of 2.5 Gbit/s are fabricated for secure free space optical communication and a free space Y-00 cipher transmission is experimentally demonstrated.
Proof of cipher text ownership based on convergence encryption
Zhong, Weiwei; Liu, Zhusong
2017-08-01
Cloud storage systems save disk space and bandwidth through deduplication technology, but with the use of this technology has been targeted security attacks: the attacker can get the original file just use hash value to deceive the server to obtain the file ownership. In order to solve the above security problems and the different security requirements of cloud storage system files, an efficient information theory security proof of ownership scheme is proposed. This scheme protects the data through the convergence encryption method, and uses the improved block-level proof of ownership scheme, and can carry out block-level client deduplication to achieve efficient and secure cloud storage deduplication scheme.
An improved permutation-diffusion type image cipher with a chaotic orbit perturbing mechanism.
Chen, Jun-xin; Zhu, Zhi-liang; Fu, Chong; Yu, Hai
2013-11-18
During the past decades, chaos-based permutation-diffusion type image cipher has been widely investigated to meet the increasing demand for real-time secure image transmission over public networks. However, the existing researches almost exclusively focus on the improvements of the permutation and diffusion methods independently, without consideration of cooperation between the two processes. In this paper, an improved permutation-diffusion type image cipher with a chaotic orbit perturbing mechanism is proposed. In the permutation stage, pixels in the plain image are shuffled with a pixel-swapping mechanism, and the pseudorandom locations are generated by chaotic logistic map iteration. Furthermore, a plain pixel related chaotic orbit perturbing mechanism is introduced. As a result, a tiny change in plain image will be spread out during the confusion process, and hence an effective diffusion effect is introduced. By using a reverse direction diffusion method, the introduced diffusion effect will be further diffused to the whole cipher image within one overall encryption round. Simulation results and extensive cryptanalysis justify that the proposed scheme has a satisfactory security with a low computational complexity, which renders it a good candidate for real-time secure image storage and distribution applications.
A Dna And Amino-Acids Based Implementation Of Four-Square Cipher
Sonal Namdev
2016-02-01
Full Text Available The DNA cryptography is a new and very promising direction in cryptographic research. It is in the primitive stage. DNA cryptography is shown to be very effective. Currently, several DNA computing algorithms are proposed for many cryptography, cryptanalysis and steganography problems, and they are very powerful in these areas. This paper discusses a significant modification of the old approach of using DNA and Amino Acids based approach with Playfair Cipher to using the same approach with different encryption algorithm, i.e; foursquare cipher to the core of the ciphering process. In this study, a binary form of data, such as plaintext messages, or images are transformed into sequences of DNA nucleotides. Subsequently, these nucleotides pass through a Foursquare encryption process based on amino-acids structure. The fundamental idea behind using this type of encryption process is to enforce other conventional cryptographic algorithms which proved to be broken, and also to open the door for applying the DNA and Amino Acids concepts to more conventional cryptographic algorithms to enhance their security features.
HYBRID CHRIPTOGRAPHY STREAM CIPHER AND RSA ALGORITHM WITH DIGITAL SIGNATURE AS A KEY
Grace Lamudur Arta Sihombing
2017-03-01
Full Text Available Confidentiality of data is very important in communication. Many cyber crimes that exploit security holes for entry and manipulation. To ensure the security and confidentiality of the data, required a certain technique to encrypt data or information called cryptography. It is one of the components that can not be ignored in building security. And this research aimed to analyze the hybrid cryptography with symmetric key by using a stream cipher algorithm and asymmetric key by using RSA (Rivest Shamir Adleman algorithm. The advantages of hybrid cryptography is the speed in processing data using a symmetric algorithm and easy transfer of key using asymmetric algorithm. This can increase the speed of transaction processing data. Stream Cipher Algorithm using the image digital signature as a keys, that will be secured by the RSA algorithm. So, the key for encryption and decryption are different. Blum Blum Shub methods used to generate keys for the value p, q on the RSA algorithm. It will be very difficult for a cryptanalyst to break the key. Analysis of hybrid cryptography stream cipher and RSA algorithms with digital signatures as a key, indicates that the size of the encrypted file is equal to the size of the plaintext, not to be larger or smaller so that the time required for encryption and decryption process is relatively fast.
Rong-Jian Chen
2010-01-01
Full Text Available This paper presents a new stream cipher for data security, which is based on permutation of the data and replacement of the data values. Permutation is done by scan patterns generated by the SCAN approach. The replacement of data values using variable ordered recursive cellular automata (CA substitutions. To achieve this aim, an encryption-specific SCAN technique was firstly developed, 2-D hybrid CA was next built, and then 1st-ordered and 2nd-ordered generalized CA transforms were introduced to build variable ordered recursive CA substitutions. The proposed stream cipher satisfies the properties of confusion and diffusion because of characteristics of the SCAN and the CA substitutions are flexible. Moreover, the characteristics of the proposed stream cipher are loss-less, symmetric private key, very large number of security keys (number of possible security keys is more than 9568 10 ~ 14785 10 - according to the size of the 2-D von Neumann CA, and key-dependent pixel value replacement. Experimental results obtained using some color images clearly demonstrate the strong performance of the proposed stream cipher. This paper also shows the DSP+FPGA implementation of the proposed stream cipher for the real-time image security.
Performance of Сellular Automata-based Stream Ciphers in GPU Implementation
P. G. Klyucharev
2016-01-01
Full Text Available Earlier the author had developed methods to build high-performance generalized cellular automata-based symmetric ciphers, which allow obtaining the encryption algorithms that show extremely high performance in hardware implementation. However, their implementation based on the conventional microprocessors lacks high performance. The mere fact is quite common - it shows a scope of applications for these ciphers. Nevertheless, the use of graphic processors enables achieving an appropriate performance for a software implementation.The article is extension of a series of the articles, which study various aspects to construct and implement cryptographic algorithms based on the generalized cellular automata. The article is aimed at studying the capabilities to implement the GPU-based cryptographic algorithms under consideration.Representing a key generator, the implemented encryption algorithm comprises 2k generalized cellular automata. The cellular automata graphs are Ramanujan’s ones. The cells of produced k gamma streams alternate, thereby allowing the GPU capabilities to be better used.To implement was used OpenCL, as the most universal and platform-independent API. The software written in C ++ was designed so that the user could set various parameters, including the encryption key, the graph structure, the local communication function, various constants, etc. To test were used a variety of graphics processors (NVIDIA GTX 650; NVIDIA GTX 770; AMD R9 280X.Depending on operating conditions, and GPU used, a performance range is from 0.47 to 6.61 Gb / s, which is comparable to the performance of the countertypes.Thus, the article has demonstrated that using the GPU makes it is possible to provide efficient software implementation of stream ciphers based on the generalized cellular automata.This work was supported by the RFBR, the project №16-07-00542.
MEMS-based seed generator applied to a chaotic stream cipher
Garcia-Bosque, M.; Pérez, A.; Sánchez-Azqueta, C.; Royo, G.; Celma, S.
2017-05-01
In this work, we have studied the possibility of using a MEMS accelerometer to generate seeds for a secure cryptosystem. The noise signal generated by the accelerometer at rest has been studied and, after a post-processing process, has been used to generate the initial parameters of a stream cipher based on a piecewise linear chaotic map. The encryption algorithm has been implemented in a Xilinx Virtex 7 FPGA achieving a throughput of 200 Mbps using 390 LUTS. The resulting sequences generated by this system have been subjected to the NIST randomness tests, passing all of them, indicating that the whole encryption system is secure.
Fides: Lightweight Authenticated Cipher with Side-Channel Resistance for Constrained Hardware
Bilgin, Begul; Bogdanov, Andrey; Knezevic, Miroslav
2013-01-01
In this paper, we present a novel lightweight authenticated cipher optimized for hardware implementations called Fides. It is an online nonce-based authenticated encryption scheme with authenticated data whose area requirements are as low as 793 GE and 1001 GE for 80-bit and 96-bit security, resp......, cryptographically optimal 5-bit and 6-bit S-boxes are used as basic nonlinear components while paying a special attention on the simplicity of providing first order side-channel resistance with threshold implementation....
Comment: Cryptanalysis of an image encryption scheme based on the Hill cipher
Cheng-qing LI; Dan ZHANG; Guan-rong CHEN
2008-01-01
This paper studies the security of an image encryption scheme based on the Hill cipher (Ismail et al.,2006) and reports its following problems:(1) There is a simple necessary and sufficient condition that makes a number of secret keys invalid;(2) It is insensitive to the change of the secret key;(3) It is insensitive to the change of the plain-image;(4) It can be broken with only one known/chosen plaintext;(5) It has some other minor defects.The proposed cryptanalysis discourages any use of the scheme in practice.
A Symmetric Chaos-Based Image Cipher with an Improved Bit-Level Permutation Strategy
Chong Fu
2014-02-01
Full Text Available Very recently, several chaos-based image ciphers using a bit-level permutation have been suggested and shown promising results. Due to the diffusion effect introduced in the permutation stage, the workload of the time-consuming diffusion stage is reduced, and hence the performance of the cryptosystem is improved. In this paper, a symmetric chaos-based image cipher with a 3D cat map-based spatial bit-level permutation strategy is proposed. Compared with those recently proposed bit-level permutation methods, the diffusion effect of the new method is superior as the bits are shuffled among different bit-planes rather than within the same bit-plane. Moreover, the diffusion key stream extracted from hyperchaotic system is related to both the secret key and the plain image, which enhances the security against known/chosen plaintext attack. Extensive security analysis has been performed on the proposed scheme, including the most important ones like key space analysis, key sensitivity analysis, plaintext sensitivity analysis and various statistical analyses, which has demonstrated the satisfactory security of the proposed scheme
Bogdanov, Andrey; Knudsen, L.R.; Leander, Gregor
2012-01-01
show that the distribution of Fourier coefficients for the cipher over all keys is close to ideal. Lastly, we define a practical instance of the construction with t = 2 using AES referred to as AES2. Any attack on AES2 with complexity below 285 will have to make use of AES with a fixed known key...
S.G.Srikantaswamy
2011-12-01
Full Text Available The process of exchanging information is called Communication. The basic Communication system involvestransmitter, receiver and the channel. The data transmitted by the sender reaches receiver through thechannel. The unauthorized parties (cracker,hacker, eavesdropper, or attacker should not be able to access the information at the channel. Therefore transmitting data securely from the sender to the receiver is a very important aspect. A cryptographic system is unconditionally secure if the cipher text produced by the system does not contain enough information to determine uniquely the corresponding plaintext, no matter how much cipher text is available. A cryptographic system is said to be computationally secure if the cost of breaking the cipher exceeds the value of the encrypted information and the time required to break the cipher exceeds the useful lifetime of the content. One time pad system can be called as unconditionally secure algorithm, if the keys (pad usedare truly random in nature. In this paper, we are demonstrating that one-time pad can be used as an efficient encryption scheme by involving arithmetic and logical operations. Here we proposed a new key generation technique, to generate a key of any length just by providing a seed value, to encrypt the message. The problem generating key value has been solved by the use of key generation algorithm.
Fengjuan CHAI; Xiao-Shan GAO; Chunming YUAN
2008-01-01
This paper presents a characteristic set method for solving Boolean equations, which is more efficient and has better properties than the general characteristic set method. In particular, the authors give a disjoint and monic zero decomposition algorithm for the zero set of a Boolean equation system and an explicit formula for the number of solutions of a Boolean equation system. The authors also prove that a characteristic set can be computed with a polynomial number of multiplications of Boolean polynomials in terms of the number of variables. As experiments, the proposed method is used to solve equations from cryptanalysis of a class of stream ciphers based on nonlinear filter generators. Extensive experiments show that the method is quite effective.
Optical stream-cipher-like system for image encryption based on Michelson interferometer.
Yang, Bing; Liu, Zhengjun; Wang, Bo; Zhang, Yan; Liu, Shutian
2011-01-31
A novel optical image encryption scheme based on interference is proposed. The original image is digitally encoded into one phase-only mask by employing an improved Gerchberg-Saxton phase retrieval algorithm together with another predefined random phase mask which serves as the encryption key. The decryption process can be implemented optically based on Michelson interferometer by using the same key. The scheme can be regarded as a stream-cipher-like encryption system, the encryption and decryption keys are the same, however the operations are different. The position coordinates and light wavelength can also be used as additional keys during the decryption. Numerical simulations have demonstrated the validity and robustness of the proposed method.
BTM: A Single-Key, Inverse-Cipher-Free Mode for Deterministic Authenticated Encryption
Iwata, Tetsu; Yasuda, Kan
We present a new blockcipher mode of operation named BTM, which stands for Bivariate Tag Mixing. BTM falls into the category of Deterministic Authenticated Encryption, which we call DAE for short. BTM makes all-around improvements over the previous two DAE constructions, SIV (Eurocrypt 2006) and HBS (FSE 2009). Specifically, our BTM requires just one blockcipher key, whereas SIV requires two. Our BTM does not require the decryption algorithm of the underlying blockcipher, whereas HBS does. The BTM mode utilizes bivariate polynomial hashing for authentication, which enables us to handle vectorial inputs of dynamic dimensions. BTM then generates an initial value for its counter mode of encryption by mixing the resulting tag with one of the two variables (hash keys), which avoids the need for an implementation of the inverse cipher.
The SAT solving method as applied to cryptographic analysis of asymmetric ciphers
Faizullin, R T; Dylkeyt, V I
2009-01-01
The one of the most interesting problem of discrete mathematics is the SAT (satisfiability) problem. Good way in SAT solver developing is to transform the SAT problem to the problem of continuous search of global minimums of the functional associated with the CNF. This article proves the special construction of the functional and offers to solve the system of non-linear algebraic equation that determines functional stationary points via modified method of consecutive approximation. The article describes parallel versions of the method. Also gives the schema of using the method to important problems of cryptographic analysis of asymmetric ciphers, including determining concrete bits of multipliers (in binary form) in large factorization problems and concrete bits of exponent of discrete logarithm problem.
Analyzing Permutations for AES-like Ciphers: Understanding ShiftRows
Beierle, Christof; Jovanovic, Philipp; Lauridsen, Martin Mehl
2015-01-01
attacks. After formalizing the concept of guaranteed trail weights, we show a range of equivalence results for permutation layers in this context. We prove that the trail weight analysis when using arbitrary word-wise permutations, with rotations as a special case, reduces to a consideration of a specific...... normal form. Using a mixed-integer linear programming approach, we obtain optimal parameters for a wide range of AES-like ciphers, and show improvements on parameters for Rijndael-192, Rijndael-256, PRIMATEs-80 and Prøst-128. As a separate result, we show for specific cases of the state geometry...... that a seemingly optimal bound on the trail weight can be obtained using cyclic rotations only for the permutation layer, i.e. in a very implementation friendly way....
Beale, Paul D
2014-01-01
We propose a new class of pseudorandom number generators based on Pohlig-Hellman exponentiation ciphers. The method generates uniform pseudorandom streams by encrypting simple sequences of short integer messages into ciphertexts by exponentiation modulo prime numbers. The advantages of the method are: the method is trivially parallelizable by parameterization with each pseudorandom number generator derived from an independent prime modulus, the method is fully scalable on massively parallel computing clusters due to the large number of primes available for each implementation, the seeding and initialization of the independent streams is simple, the method requires only a few integer multiply-mod operations per pseudorandom number, the state of each instance is defined by only a few integer values, the period of each instance is different, and the method passes a battery of intrastream and interstream correlation tests using up to $10^{13}$ pseudorandom numbers per test. We propose an implementation using 32-b...
Design and implementation of a high-speed reconfigurable cipher chip
Gao Nana; Li Zhancai; Wang Qin
2006-01-01
A reconfigurable cipher chip for accelerating DES is described, 3DES and AES computations that demand high performance and flexibility to accommodate large numbers of secure connections with heterogeneous clients. To obtain high throughput, we analyze the feasibility of high-speed reconfigurable design and find the key parameters affecting throughput. Then, the corresponding design, which includes the reconfiguration analysis of algorithms, the design of reconfigurable processing units and a new reconfigurable architecture based on pipeline and parallel structure, are proposed. The implementation results show that the operating frequency is 110 MHz and the throughput rate is 7 Gbps for DES, 2.3 Gbps for 3 DES and 1.4 Gbps for AES. Compared with the similar existing implementations, our design can achieve a higher performance.
Synthesis Optimization on Galois-Field Based Arithmetic Operators for Rijndael Cipher
Petrus Mursanto
2011-08-01
Full Text Available A series of experiments has been conducted to show that FPGA synthesis of Galois-Field (GF based arithmetic operators can be optimized automatically to improve Rijndael Cipher throughput. Moreover, it has been demonstrated that efficiency improvement in GF operators does not directly correspond to the system performance at application level. The experiments were motivated by so many research works that focused on improving performance of GF operators. Each of the variants has the most efficient form in either time (fastest or space (smallest occupied area when implemented in FPGA chips. In fact, GF operators are not utilized individually, but rather integrated one to the others to implement algorithms. Contribution of this paper is to raise issue on GF-based application performance and suggest alternative aspects that potentially affect it. Instead of focusing on GF operator efficiency, system characteristics are worth considered in optimizing application performance.
MULTI-BLOCK CHAINING-BASED AUTHENTICATION MODE
Huang Yuhua; Hu Aiqun; Zhong Ziguo
2006-01-01
A fast authentication mode based on Multi-Block Chaining (MBC) is put forward; and its security is proved. The MBC mode is for new generation block cipher algorithms. Its speed is about 13% faster than that of the authentication modes in common use (for example, cipher block chaining-message authentication code mode). The dependence test results meet the requirement. The MBC mode is complete; its degree of avalanche effect is about 0.9993; its degree of strict avalanche criterion is 0.992 or so. The frequency test results indicate that the output generated by the MBC mode has uniformity. The binary matrix rank test results imply that it is linear independent among disjoint sub-matrices of the output. Maurer's universal statistical test results show that the output could be significantly compressed without loss of information. Run test, spectral test,non-overlapping template matching test, overlapping template matching test, Lempel-Ziv compression test,linear complexity test, serial test, approximate entropy test, cumulative sums test, random excursions test and random excursions variant test results fulfill the requirements of all. Therefore the MBC mode has good pseudo-randomness. Thus the security of MBC mode is verified by the way of statistical evaluation.
Fallahi, Kia; Raoufi, Reza; Khoshbin, Hossein
2008-07-01
In recent years chaotic secure communication and chaos synchronization have received ever increasing attention. In this paper a chaotic communication method using extended Kalman filter is presented. The chaotic synchronization is implemented by EKF design in the presence of channel additive noise and processing noise. Encoding chaotic communication is used to achieve a satisfactory, typical secure communication scheme. In the proposed system, a multi-shift cipher algorithm is also used to enhance the security and the key cipher is chosen as one of the chaos states. The key estimate is employed to recover the primary data. To illustrate the effectiveness of the proposed scheme, a numerical example based on Chen dynamical system is presented and the results are compared to two other chaotic systems.
Hirota, Osamu; Futami, Fumio
2014-10-01
To guarantee a security of Cloud Computing System is urgent problem. Although there are several threats in a security problem, the most serious problem is cyber attack against an optical fiber transmission among data centers. In such a network, an encryption scheme on Layer 1(physical layer) with an ultimately strong security, a small delay, and a very high speed should be employed, because a basic optical link is operated at 10 Gbit/sec/wavelength. We have developed a quantum noise randomied stream cipher so called Yuen- 2000 encryption scheme (Y-00) during a decade. This type of cipher is a completely new type random cipher in which ciphertext for a legitimate receiver and eavesdropper are different. This is a condition to break the Shannon limit in theory of cryptography. In addition, this scheme has a good balance on a security, a speed and a cost performance. To realize such an encryption, several modulation methods are candidates such as phase-modulation, intensity-modulation, quadrature amplitude modulation, and so on. Northwestern university group demonstrated a phase modulation system (α=η) in 2003. In 2005, we reported a demonstration of 1 Gbit/sec system based on intensity modulation scheme(ISK-Y00), and gave a design method for quadratic amplitude modulation (QAM-Y00) in 2005 and 2010. An intensity modulation scheme promises a real application to a secure fiber communication of current data centers. This paper presents a progress in quantum noise randomized stream cipher based on ISK-Y00, integrating our theoretical and experimental achievements in the past and recent 100 Gbit/sec(10Gbit/sec × 10 wavelengths) experiment.
基于正交拟群的流密码算法%Stream Cipher Based on Mutually Orthogonal Quasigroups
张晓燕; 徐允庆
2016-01-01
利用正交拟群的特点，克服Edon80的弱点，设计了称为Double40的二进制加法同步流密码算法。它基于一对8阶相互正交的自正交拟群，使得 Johansson 和 Hell 的密钥恢复攻击对Double40无法奏效。%Edon80 is a hardware binary additive synchronous stream cipher submitted to the last phase of the eSTREAM project. The core of the cipher consists of quasigroup string e-transformations and employs four quasigroups of order 4. The best attack on Edon80 is the key recovery attack given by Johansson and Hell, which can recover the key with complexity around 272. In this paper, using the characteristics of orthogonal quasigroup to overcome the shorting of Edon80, a binary additive synchronous stream cipher named Double40 is designed. It is based on a pair of mutually orthogonal quasigroups of order 8 which are self-orthogonal. The developed algorithm disables the key recovery attack of Johansson and Hell on Double40.
分组密码S盒的代数方程%Algebraic equations of S-box block cipher
李伟博; 解永宏; 胡磊
2008-01-01
研究了几种著名的分组密码体制的S盒所满足的代数方程的个数,如DES、AES、MARS、SERPENT等,分别计算出这几种分组密码的S盒从低次到高次的代数方程的个数,并把计算结果和理论极小值进行了比较.此外,还针对一类对密码分析具有特别意义的不完全代数方程研究了S盒所满足的这类不完全代数方程的个数,通过这类方程的个数,可以看到它们的S盒与随机S盒的差别.
Improved Asymmetric Cipher Based on Matrix Power Function with Provable Security
Eligijus Sakalauskas
2017-01-01
Full Text Available The improved version of the author’s previously declared asymmetric cipher protocol based on matrix power function (MPF is presented. Proposed modification avoids discrete logarithm attack (DLA which could be applied to the previously declared protocol. This attack allows us to transform the initial system of MPF equations to so-called matrix multivariate quadratic (MMQ system of equations, which is a system representing a subclass of multivariate quadratic (MQ systems of equations. We are making a conjecture that avoidance of DLA in protocol, presented here, should increase its security, since an attempt to solve the initial system of MPF equations would appear to be no less complex than solving the system of MMQ equations. No algorithms are known to solve such a system of equations. Security parameters and their secure values are defined. Security analysis against chosen plaintext attack (CPA and chosen ciphertext attack (CCA is presented. Measures taken to prevent DLA attack increase the security of this protocol with respect to the previously declated protocol.
A new substitution-diffusion based image cipher using chaotic standard and logistic maps
Patidar, Vinod; Pareek, N. K.; Sud, K. K.
2009-07-01
In this paper, we propose a new loss-less symmetric image cipher based on the widely used substitution-diffusion architecture which utilizes chaotic standard and logistic maps. It is specifically designed for the coloured images, which are 3D arrays of data streams. The initial condition, system parameter of the chaotic standard map and number of iterations together constitute the secret key of the algorithm. The first round of substitution/confusion is achieved with the help of intermediate XORing keys calculated from the secret key. Then two rounds of diffusion namely the horizontal and vertical diffusions are completed by mixing the properties of horizontally and vertically adjacent pixels, respectively. In the fourth round, a robust substitution/confusion is accomplished by generating an intermediate chaotic key stream (CKS) image in a novel manner with the help of chaotic standard and logistic maps. The security and performance of the proposed image encryption technique has been analyzed thoroughly using various statistical analysis, key sensitivity analysis, differential analysis, key space analysis, speed analysis, etc. Results of the various types of analysis are encouraging and suggest that the proposed image encryption technique is able to manage the trade offs between the security and speed and hence suitable for the real-time secure image and video communication applications.
Chaotic Stream Cipher-Based Secure Data Communications over Intelligent Transportation Network
Wei Zhang
2015-01-01
Full Text Available Intelligent transportation systems (ITS are advanced applications in which the transportation industry is adapted to the information technology revolution. As an important development direction of ITS, the electronic toll collection (ETC subsystem, which enables an efficient and speedy toll collection, has gained widespread popularity in the world. In an ETC system, toll transaction data are transmitted over intelligent transportation networks, which is vulnerable to eavesdropping, interfering, and tampering attacks. To address the above security problems, we proposed a chaotic stream cipher-based cryptographic scheme to realise secure data communications over wireless sensor network (WSN, which is a part of ITS. The proposed cryptographic scheme allowed ITS to achieve key negotiation and data encryption between sensor nodes in the WSN, whileas reduced computational costs and power consumption. Security analysis and experimental results showed that the proposed scheme could protect data transmission between wireless sensor nodes from being attacked, and significantly reduced the communication overhead for the whole system compared to the existing ECC_AES scheme, thus satisfying the real-time data transmission requirement of ITS.
Pseudorandom Bit Sequence Generator for Stream Cipher Based on Elliptic Curves
Jilna Payingat
2015-01-01
Full Text Available This paper proposes a pseudorandom sequence generator for stream ciphers based on elliptic curves (EC. A detailed analysis of various EC based random number generators available in the literature is done and a new method is proposed such that it addresses the drawbacks of these schemes. Statistical analysis of the proposed method is carried out using the NIST (National Institute of Standards and Technology test suite and it is seen that the sequence exhibits good randomness properties. The linear complexity analysis shows that the system has a linear complexity equal to the period of the sequence which is highly desirable. The statistical complexity and security against known plain text attack are also analysed. A comparison of the proposed method with other EC based schemes is done in terms of throughput, periodicity, and security, and the proposed method outperforms the methods in the literature. For resource constrained applications where a highly secure key exchange is essential, the proposed method provides a good option for encryption by time sharing the point multiplication unit for EC based key exchange. The algorithm and architecture for implementation are developed in such a way that the hardware consumed in addition to point multiplication unit is much less.
Physical-layer security analysis of PSK quantum-noise randomized cipher in optically amplified links
Jiao, Haisong; Pu, Tao; Xiang, Peng; Zheng, Jilin; Fang, Tao; Zhu, Huatao
2017-08-01
The quantitative security of quantum-noise randomized cipher (QNRC) in optically amplified links is analyzed from the perspective of physical-layer advantage. Establishing the wire-tap channel models for both key and data, we derive the general expressions of secrecy capacities for the key against ciphertext-only attack and known-plaintext attack, and that for the data, which serve as the basic performance metrics. Further, the maximal achievable secrecy rate of the system is proposed, under which secrecy of both the key and data is guaranteed. Based on the same framework, the secrecy capacities of various cases can be assessed and compared. The results indicate perfect secrecy is potentially achievable for data transmission, and an elementary principle of setting proper number of photons and bases is given to ensure the maximal data secrecy capacity. But the key security is asymptotically perfect, which tends to be the main constraint of systemic maximal secrecy rate. Moreover, by adopting cascaded optical amplification, QNRC can realize long-haul transmission with secure rate up to Gb/s, which is orders of magnitude higher than the perfect secrecy rates of other encryption systems.
Equivalence of the Random Oracle Model and the Ideal Cipher Model, Revisited
Holenstein, Thomas; Tessaro, Stefano
2010-01-01
We consider the cryptographic problem of constructing an invertible random permutation from a public random function (i.e., which can be accessed by the adversary). This goal is formalized by the notion of indifferentiability of Maurer et al. (TCC 2004). This is the natural extension to the public setting of the well-studied problem of building random permutations from random functions, which was first solved by Luby and Rackoff (Siam J. Comput., '88) using the so-called Feistel construction. The most important implication of such a construction is the equivalence of the random oracle model (Bellare and Rogaway, CCS '93) and the ideal cipher model, which is typically used in the analysis of several constructions in symmetric cryptography. Coron et al. (CRYPTO 2008) gave a rather involved proof that the six-round Feistel construction with independent random round functions is indifferentiable from an invertible random permutation. Also, it is known that fewer than six rounds do not suffice for indifferentiabil...
Image Encryption Using Stream Cipher Based on Nonlinear Combination Generator with Enhanced Security
Belmeguenaï Aîssa
2013-03-01
Full Text Available The images are very largely used in our daily life; the security of their transfer became necessary. In this work a novel image encryption scheme using stream cipher algorithm based on nonlinear combination generator is developed. The main contribution of this work is to enhance the security of encrypted image. The proposed scheme is based on the use the several linear feedback shifts registers whose feedback polynomials are primitive and of degrees are all pairwise coprimes combined by resilient function whose resiliency order, algebraic degree and nonlinearity attain Siegenthaler’s and Sarkar, al.’s bounds. This proposed scheme is simple and highly efficient. In order to evaluate performance, the proposed algorithm was measured through a series of tests. These tests included visual test and histogram analysis, key space analysis, correlation coefficient analysis, image entropy, key sensitivity analysis, noise analysis, Berlekamp-Massey attack, correlation attack and algebraic attack. Experimental results demonstrate the proposed system is highly key sensitive, highly resistance to the noises and shows a good resistance against brute-force, statistical attacks, Berlekamp-Massey attack, correlation attack, algebraic attack and a robust system which makes it a potential candidate for encryption of image.
Turner, W.
2007-01-01
Consider representation theory associated to symmetric groups, or to Hecke algebras in type A, or to q-Schur algebras, or to finite general linear groups in non-describing characteristic. Rock blocks are certain combinatorially defined blocks appearing in such a representation theory, first observed by R. Rouquier. Rock blocks are much more symmetric than general blocks, and every block is derived equivalent to a Rock block. Motivated by a theorem of J. Chuang and R. Kessar in the case of sym...
Futami, Fumio; Kato, Kentaro; Hirota, Osamu
2016-09-01
For protecting physical layer of optical fiber communication systems, quantum stream cipher called Y-00 and Alpha-Eta is promising. So far, we demonstrated secure and high speed optical fiber communication experiments using Y-00 quantum stream cipher. Our theoretical research revealed that the randomization techniques could enhance the security performance. In this work, we fabricated a novel Y-00 transceiver for GbE where the randomization technique was implemented. The transceiver employed the optical intensity modulated Y-00 quantum stream cipher with intensity levels of 4096. An appropriately designed irregular mapping as the randomization technique was experimentally demonstrated. The transceiver was successfully applied to secure optical fiber transmission of GbE signals.
Block Based Symmetry Key Visual Cryptography
Satyendra Nath Mandal
2012-08-01
Full Text Available Visual cryptography is a method for protecting image-based secrets that has a computation-free decoding process. In this technique, numbers of shares have been generated from one image. The shares are sent through any channel to the receiver and the receiver can again produce original image by stacking all the shares in proper order. But, this method wastes a lot of bandwidth of the network. The techniques of generating shares have been used in several existing methods which are not unique. The different methods have been used in different types of images like binary, gray and color images. In this paper, a block based symmetry key visual cryptography algorithm has been proposed to convert image in encrypted form and decrypt the encrypted image into original form. The symmetric key has been generated from a real number. The encryption and decryption algorithm have been designed based on symmetry key. The algorithm with key has been used to encrypt image into single share and decrypt the single share into original image. The real number has been used to form the key may be predefined or may be sent by secure channel to the receiver. The proposed algorithm can be applied to any type images i.e. binary, gray scale and color images. A comparison has been made of the proposed algorithm with different existing algorithms like Ceaser cipher, transpose of matrix, bit comp, and transposition cipher based on the performance. The pixels distributed in original and share images have also been tested. Finally, it has shown that breaking of security level of proposed algorithm i.e. to guess the real number is huge time consuming.
Prof. R. Venkateswaran
2011-09-01
Full Text Available prevent detection of hidden messages. Secure data transmission method, which tries to alter the originality of the data files in to some encrypted form by using different methods and techniques. Encryption of data plays a vital role in the real time environment to keep the data out of reach of unauthorized people. After encryption, the files can be transferred securely by using multiple cytological methods. In this Paper embed and de-embed processes of information hiding in various file format and carried out analysis in different approach and procedures are implemented in developing novel information security system in multimedia files like image and video, video file and other methods. Varieties of techniques for embedding information in digital audio /video have been established. In this paper we will attend the general principles and different methodology adopted based on e -cipher model for hiding secret information using cryptographic technology, and an overview of functions and techniques, the goal of this paper is to know the different areas of information hiding and tools for providing secure data transmission with proposed e-cipher algorithms.
Smith, Martin H.
1992-01-01
Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…
Smith, Martin H.
1992-01-01
Describes an educational game called "Population Blocks" that is designed to illustrate the concept of exponential growth of the human population and some potential effects of overpopulation. The game material consists of wooden blocks; 18 blocks are painted green (representing land), 7 are painted blue (representing water); and the remaining…
基于FPGA的eStream序列密码实现分析%Implementation of FPGA-based eStream Sequential Cipher
徐远泽; 张文科; 尹一桦; 罗影
2015-01-01
The project of Europe eStream sequential cipher promotes the development of modern stream ci-pher, and the researchers of sequential cipher turn their attention to the design of light-weight stream ci-pher liable to hardware implementation. Grain-128, MICKEY2. 0 and TRIVIUM, these three stream ci-phers oriented to hardware implementation recommended by eStream sequential cipher are studied. Firstly, the basic principles of these three stream ciphers are presented, then their circuit configurations designed on FPGA,and finally,their comprehensive implementations are done on Xilinx Virtex-5 of FPGA platform with Verilog HDL language. Implementation result indicates that,of the three algorithms,TRIVIUM occu-pies the least FPGA logic resources while enjoying the highest throughput,and MICKEY2. 0 occupies the highest logic resources while enjoying the lowest throughput.%欧洲eStream序列密码计划推动了现代序列密码的发展,序列密码研究开始关注于易于硬件实现的轻量化序列密码设计。主要研究了eStream序列密码推荐的三种面向硬件实现的密码算法：Grain-128、MICKEY2.0和TRIVIUM。首先分别介绍了三种算法的基本原理,然后针对每种算法进行FPGA下的电路结构设计,最后采用Verilog HDL语言,在Xilinx Virtex-5 FPGA平台上进行了综合实现。实现结果表明,在三种算法中,TRIVIUM算法占用FPGA逻辑资源最少,其吞吐量最高,而MICKEY2.0算法占用FPGA逻辑资源最多,同时吞吐量最低。
无
1996-01-01
@@ The Zitongdong Block (Eastern Zitong Block) is located in the northwest of the Sichuan Basin. Tectonically, it is situated in the east part of Zitong Depression, southeast of mid-Longmenshan folded and faulted belt( as shown on Fig. 8 ), covering an area of 1 730 km2. The traffic is very convenient, the No. 108 national highway passes through the north of the block. Topographically, the area belongs to low hilly land at the elevation of 500-700 m.
无
1996-01-01
@@ Zitongxi Block (Western Zitong Block), is located in Zitong County, northwest of Sichuan Province (as shown on Fig. 8 ). Geologically. it is situated in the Zitong Depression, southwest of the middle Longmenshan faulted and folded belt, covering an area of 1 830 km2. Transportation is very convenient. A crisscross network of highways run through the block and the Baocheng railway is nearby. The climate is moderate. Most area belongs to hilly land with the elevation of 500-600 m.The Tongjiang River runs across the area.
无
1996-01-01
@@ Chengzikou Block is located in the north of Hekou district, Dongying City, Shandong Province, adjacent to Bohai Bay. It can be geographically divided into three units: onshore, transitional zone and offshore ultrashallow zone, totally covering an area of 470 km2. The southern onshore area is low and gentle in topography;the northern shallow sea is at water depths of 2-8 m below sea level, and the transitional zone occupies more than 60% of the whole block. The climate belongs to temperate zone with seasonal wind. Highways are welldeveloped here, and the traffic is very convenient. The Chengzikou Block is about 80 km away from Dongying City and 290 km from Jinan City in the south. The northern offshore area of the block is 160 km away from Longkou port in the east and only 38 km away in the west from Zhuangxi port.
云计算安全中密码技术应用模型研究%Application Model of Cipher Technology in Cloud Computing Security
尹一桦; 张文科; 王斯梁
2014-01-01
Firstly,this paper briefly analyzes the principle of cloud computing and the new security problem brought by cloud computing. Based on this,the security structure of cloud computing is discussed,and the application approaches of cipher technology are presented. Secondly, in view of work flow of security sys-tem, an application model of cipher technology is given in combination with security architecture in cloud computing and encryption theory. Finally, the cipher application and its devlopment in cloud computing security are summarized, this could provide a practicable solution for cipher technology application in cloud computing security.%首先简要分析了云计算的工作原理及可能带来的安全隐患，在此基础上探讨了云计算环境下的安全架构，并给出了密码技术的应用途径。其次，从云计算环境下的安全系统工作流程这个维度，结合密码学理论、云计算安全架构给出了在云计算安全中密码技术的应用模型。最后，归纳出基于该模型的云计算环境中密码应用技术及其发展趋势，为密码技术应用于云计算安全中提供可用的解决思路。
无
1996-01-01
@@ Longmenshan Block is located in Jiange County of Jiangyou City in the northwest of Sichuan Basin. covering an area of 2 628 km2. Geologically, it is situated in the Mid-Longmenshan fault and fold belt, neighbouring Zitong Depression in its southeast. There are mountains surrounding its northwest , the rest area being hilly land,with the elevation of 500-700 m. The BaoCheng railway and the No. 108 highway run through the block, the traffic is very convenient.
潘志鹏; 吴斌; 尉志伟; 叶甜春
2015-01-01
针对IEEE 802.11i协议中多种安全协议实现进行研究,结合以IEEE 802.11ac协议为代表的下一代无线局域网( WLAN)系统对高吞吐率的需求,提出了一种支持WEP/TKIP/CCMP协议的多模、高速安全加速引擎的大规模集成电路( VLSI)架构. 提出了基于哈希算法的密钥信息查找算法,缩小了查找时钟延迟. 基于复合域的运算方式实现高级加密标准( AES)算法,提出双AES运算核的并行架构实现计数器与密码分组链接( CCM)模式,提升运算吞吐率的同时也降低了引擎的响应延迟. 经过FPGA实现和ASIC流片验证表明,该安全加速引擎具备可重构性,处理延迟仅为33个时钟周期,在322 MHz工作频率下运算吞吐率可达3.747 Gbit/s.%In this paper, the implementation of multiple security protocols for IEEE 802.11i was researched. A very large scale integration ( VLSI) architecture of the multi-mode cipher engine supporting WEP/TKIP/CCMP proto-cols was presented taking into account the demand for high throughput of the next generation wireless local area net-work ( WLAN) system that is represented by IEEE 802.11ac. A key searching algorithm based on Hash scheme was proposed to reduce the lookup clock latency. For the high throughput hardware implementation of advanced encryp-tion standard ( AES) algorithm, composite field arithmetic was employed. In order to improve the data throughput and reduce the response time, dual AES computing core with parallel structure was used to implement the cipher block chaining message authentication code ( CCM) mode. The proposed design was implemented in both FPGA and ASIC. The results show that the cipher engine with reconfiguration architecture can achieve 33 clock cycles, and the computing throughput is 3.747 Gbit/s when the work frequency is 322 MHz.
无
1996-01-01
@@ The Chadong Block, located in the east of Qaidam Basin, Qinghai Province, covers an area of 12 452 km2. It is bounded by Kunlum Mountains in the south and the northwest is closely adjacent to Aimunike Mountain.Rivers are widely distributed, which always run in NWSE direction, including the Sulunguole, Qaidam and Haluwusu Rivers. The traffic condition is good, the Qinghai-Tibet highway stretching through the whole area and the Lan-Qing railway, 20-50 km away from the block, passing from north to west. A lot of Mongolia minority people have settled there, of which herdsmen always live nearby the Qaidam River drainage area.
Rojali, Salman, Afan Galih; George
2017-08-01
Along with the development of information technology in meeting the needs, various adverse actions and difficult to avoid are emerging. One of such action is data theft. Therefore, this study will discuss about cryptography and steganography that aims to overcome these problems. This study will use the Modification Vigenere Cipher, Least Significant Bit and Dictionary Based Compression methods. To determine the performance of study, Peak Signal to Noise Ratio (PSNR) method is used to measure objectively and Mean Opinion Score (MOS) method is used to measure subjectively, also, the performance of this study will be compared to other method such as Spread Spectrum and Pixel Value differencing. After comparing, it can be concluded that this study can provide better performance when compared to other methods (Spread Spectrum and Pixel Value Differencing) and has a range of MSE values (0.0191622-0.05275) and PSNR (60.909 to 65.306) with a hidden file size of 18 kb and has a MOS value range (4.214 to 4.722) or image quality that is approaching very good.
An Efficient Image Encryption Scheme Based on a Peter De Jong Chaotic Map and a RC4 Stream Cipher
Hanchinamani, Gururaj; Kulkarni, Linganagouda
2015-09-01
Security is a vital issue in communication and storage of the images and encryption is one of the ways to ensure the security. This paper proposes an efficient image encryption scheme based on a Peter De Jong chaotic map and a RC4 stream cipher. A Peter De Jong map is employed to determine the initial keys for the RC4 stream generator and also during permutation stage. The RC4 stream generator is utilized to generate the pseudo random numbers for the pixel value rotation and diffusion operations. Each encryption round is comprised of three stages: permutation, pixel value rotation and diffusion. The permutation is based on scrambling the rows and columns, in addition, circular rotations of the rows and columns in alternate orientations. The second stage circularly rotates each and every pixel value by utilizing M × N pseudo random numbers. The last stage carries out the diffusion twice by scanning the image in two different ways. Each of the two diffusions accomplishes the diffusion in two orientations (forward and backward) with two previously diffused pixels and two pseudo random numbers. The security and performance of the proposed method is assessed thoroughly by using key space, statistical, differential, entropy and performance analysis. Moreover, two rounds of the call to the encrypt function provide the sufficient security. The experimental results show that the proposed encryption scheme is computationally fast with high security.
Slide Attack on Modified Trivium Stream Cipher%修改Trivium流密码算法的滑动攻击
关杰; 丁林
2012-01-01
基于求解非线性方程组，对Sonmez等提出的修改Trivium算法进行了滑动攻击，找到了多于2^85的滑动对，远远大于原Trivium算法的滑动对数（2^39）．在假设获得一个滑动对的基础上，攻击者可以恢复出修改Trivium算法的全部80bit密钥，计算复杂度为0（2^35）．%A slide attack on modified Trivium stream cipher presented by Sonmez et. al. based on solving nonlinear equations was present. The result shows that there exist more than 2^85 slide pairs in the modified Trivium, which is much more than 239 slide pairs in the original Trivium. If a slide pair is obtained, the at- tacker can recover the 80-bit initial key of modified Trivium with a computational complexity of O（2^35）.
Muralee, Krishnan C. R.
2008-10-01
This symmetric key algorithm and its implementation convert manually entered password into mathematical expression, which is further used to generate an infinitely non-repetitive sequence of presumably random characters. These random series of characters are used to encrypt the data. This encrypted data stream is in turn swapped by dividing the data, block by block and the size of the blocks keep changing from the beginning of the data to the end of the data. The swapping commences from the beginning of the encryption and proceeds. The size of the block for swapping is narrow compared to the full length of the data and entirely depends on the one of the earlier characters which has already got swapped away from its initial position. All the characters will be mapped uniquely to mathematical expressions of a set of parameters in a pool of 256 expressions. These expressions corresponding to all characters in a password are added together to obtain a resultant expression. The above mentioned expressions corresponding to each character are further modified in advance (before summing up together) by including a `position index'. This is inevitable to take care of the repetition of characters within a password and also in the case of a permutated password. In the case of permutated passwords, the random characters generated should be different in each case. In another words, each character and its position in the password have its own unique identity. Two pools of mathematical expressions are employed, coupled with different initiations to the parameters, to get a couple of pseudorandom character series, one's value being fed to the other. These are XORed together giving rise to a random series passing the popularly available randomness tests done by Nernst and Die hard. The initiating vector will be using, possibly the system time, and annexed with the original password to get the modified password. The system is similar to the conventional IV manipulation. The swapping
Secure chaotic map based block cryptosystem with application to camera sensor networks.
Guo, Xianfeng; Zhang, Jiashu; Khan, Muhammad Khurram; Alghathbar, Khaled
2011-01-01
Recently, Wang et al. presented an efficient logistic map based block encryption system. The encryption system employs feedback ciphertext to achieve plaintext dependence of sub-keys. Unfortunately, we discovered that their scheme is unable to withstand key stream attack. To improve its security, this paper proposes a novel chaotic map based block cryptosystem. At the same time, a secure architecture for camera sensor network is constructed. The network comprises a set of inexpensive camera sensors to capture the images, a sink node equipped with sufficient computation and storage capabilities and a data processing server. The transmission security between the sink node and the server is gained by utilizing the improved cipher. Both theoretical analysis and simulation results indicate that the improved algorithm can overcome the flaws and maintain all the merits of the original cryptosystem. In addition, computational costs and efficiency of the proposed scheme are encouraging for the practical implementation in the real environment as well as camera sensor network.
Study on Application of Commercial Cipher Cloud Storage System%商密云存储系统应用研究
汪来富; 沈军; 金华敏
2012-01-01
This paper analyzes the security requirements faced by cloud storage and its application,proposes the commercial cipher cloud storage system based on the commercial cipher technology and cloud storage technology. It describes in detail the architecture and function design of this system and the security design for guarantee of the whole process security of user data through implementing the mechanisms of high-strength authentication,data encryption storage,unified key management,data transfer encryption and security isolation. Finally,this paper proposes the service contents and forms of commercial cipher cloud storage products from the two aspects of enterprise customers and public customers.%分析了云存储及其应用面临的安全需求,提出了以商用密码和云存储技术为基础的商密云存储业务系统。系统地介绍了商密云存储业务系统的系统架构及功能设计,并通过实施高强度安全认证、数据加密存储、统一密钥管理、数据传输加密以及安全隔离等安全机制,保障用户数据在网络传输、处理、存储等全流程的安全,最后从政企客户和公众客户两个层面提出商密云存储产品的服务形态设计思路。
加密算法Serpent的线性变换的一些性质%SOME PROPERTIES OF THE LINEAR TRANSFORMATION OFTHE BLOCK CIPHER SERPENT
王林
2002-01-01
对加密算法Serpent中的线性变换进行了仔细的研究,证明了该线性变换的一些性质.根据这些性质,并引进Λ-集合和影响集的概念,得到了对于3轮Serpent加密算法实施Square攻击的如下步骤:①获取满足一定条件的16个明文分组所对应的密文分组;②任意选取128位的密钥K3,并求其上述16个密文分组的异或;③对所得到的16个分组施行S2的逆变换;④求这16个分组的按位异或,若为0,则说明②中所选取的K3是正确的,否则返回②. 该攻击法需要16个选择明文分组和平均2127的异或运算和S2逆变换. 其中S2表示第2轮的S-盒变换.
基于分组密码的物理层加密通信系统%Physical-layer encryption communication systems with block ciphers
郭晶; 王剑; 袁坚; 山秀明; 任勇
2011-01-01
Traditional secure communication systems separate the channel coding and cryptography so security is not affected by channel errors. This paper presents a design method based on physical-layer encryption to further improve system security by introducing channel errors into the cryptography. This paper also presents a method to quantitatively evaluate this system secrecy by calculating the impact of channel errors and correlations in codewords as a new technical evaluation method for similar systems. Theoretical and simulation results show that when the bit error rate for the binary systemetric channel （BSC） is larger than a threshold, the system in this paper is more secure than traditional systems.%传统安全通信系统分别设计信道编码、密码算法等模块，系统安全性几乎不受信道误码影响。借鉴物理层加密的概念，该文提出一种系统化设计方法，利用信道误码进一步提高系统安全性。提出对该系统进行安全性定量评估的方法，分别计算码字相关性和信道误码对安全性的影响，为研究该类系统提供了新的技术途径。理论和仿真结果表明：当二进制对称信道（BSC）的比特翻转概率大于阈值时，所设计的基于分组密码的物理层加密通信系统具有高于传统安全通信系统的安全性。
Diffie, W; Field, J
2015-01-01
This detailed technical account of breaking Tunny is an edition of a report written in 1945, with extensive modern commentary Breaking Teleprinter Ciphers at Bletchley Park gives the full text of the General Report on Tunny (GRT) of 1945, making clear how the ideas, notation and the specially designed machines that were used differ from what was generally accepted in 1945, and, where a modern reader might be misled, from what is understood now. The editors of this book clarify the sometimes slightly strange language of the GRT and explain the text within a variety of contexts in several separate historical story lines, some only implicit in the GRT itself. The first story, told by the authors of the GRT, describes how, using specially designed machines, including from 1944 the "Colossus", the British broke the enciphered teleprinter messages sent by the highest command levels of the Germany Army. The cipher machines the Germans used were the Loren SZ 40 series, called "Tunny" by the British. The second stor...
New Methods for Statistical Analysis of Stream Ciphers%对序列密码统计测试的新方法
李恒; 李瑞林; 谢端强
2012-01-01
对密钥流的统计分析是序列密码算法设计与分析中的重要内容。文中从随机布尔函数和随机向量值函数的Walsh谱的分布特性出发，对同步序列密码提出了两种新的选择IV统计分析方法。并利用这些新方法对入选eSTREAM计划的Grainv0、Grainvl和Trivium算法进行了统计测试。结果表明，Grainv0和Grainv1的伪随机性没有达到最好。%Statistical analysis of the key-stream is an important part in the design and analysis of stream ciphers. This paper proposes two new methods for chosen-IV statistical analysis of synchronous stream ciphers based on the distribution of Walsh Transform of random Boolean functions and random vectorial Boolean functions. These methods are used to analyze Grain v0, Grain v1 and Trivium, which are selected into the eSTREAM project. The results show that the pseudo-randomness of Grain v0 and Grain vl couldn't reach the ideal case.
Rehman, Sadaqat Ur; Ahmad, Basharat; Yahya, Khawaja Muhammad; Ullah, Anees; Rehman, Obaid Ur
2012-01-01
Wireless Sensor Networks (WSN) are becoming popular day by day, however one of the main issue in WSN is its limited resources. We have to look to the resources to create Message Authentication Code (MAC) keeping in mind the feasibility of technique used for the sensor network at hand. This research work investigates different cryptographic techniques such as symmetric key cryptography and asymmetric key cryptography. Furthermore, it compares different encryption techniques such as stream cipher (RC4), block cipher (RC2, RC5, RC6 etc) and hashing techniques (MD2, MD4, MD5, SHA, SHA1 etc). The result of our work provides efficient techniques for communicating device, by selecting different comparison matrices i.e. energy consumption, processing time, memory and expenses that satisfies both the security and restricted resources in WSN environment to create MAC.
Sadaqat Ur Rehman
2012-01-01
Full Text Available Wireless Sensor Networks (WSN are becoming popular day by day, however one of the main issue in WSN is its limited resources. We have to look to the resources to create Message Authentication Code (MAC and need to choose a technique which is feasible for sensor networks. This research work investigates different cryptographic techniques such as symmetric key cryptography and asymmetric key cryptography, furthermore it compares different encryption techniques such as stream cipher (RC4, block cipher (RC2, RC5, RC6 etc and hashing techniques (MD2, MD4, MD5, SHA, SHA1 etc. The result of our work provides efficient techniques for communicator, by selecting different comparison matrices i.e. energy consumption, processing time, memory and expenses that satisfies both the security and restricted resources in WSN environment to create MAC
Ultrasound guided supraclavicular block.
Hanumanthaiah, Deepak
2013-09-01
Ultrasound guided regional anaesthesia is becoming increasingly popular. The supraclavicular block has been transformed by ultrasound guidance into a potentially safe superficial block. We reviewed the techniques of performing supraclavicular block with special focus on ultrasound guidance.
Efficient Hardware Implementation of the Lightweight Block Encryption Algorithm LEA
Donggeon Lee
2014-01-01
Full Text Available Recently, due to the advent of resource-constrained trends, such as smartphones and smart devices, the computing environment is changing. Because our daily life is deeply intertwined with ubiquitous networks, the importance of security is growing. A lightweight encryption algorithm is essential for secure communication between these kinds of resource-constrained devices, and many researchers have been investigating this field. Recently, a lightweight block cipher called LEA was proposed. LEA was originally targeted for efficient implementation on microprocessors, as it is fast when implemented in software and furthermore, it has a small memory footprint. To reflect on recent technology, all required calculations utilize 32-bit wide operations. In addition, the algorithm is comprised of not complex S-Box-like structures but simple Addition, Rotation, and XOR operations. To the best of our knowledge, this paper is the first report on a comprehensive hardware implementation of LEA. We present various hardware structures and their implementation results according to key sizes. Even though LEA was originally targeted at software efficiency, it also shows high efficiency when implemented as hardware.
Software encryption: new 64-bit block cryptoscheme
A. Moldovyan
1997-01-01
Full Text Available There are considered new fast software encryption function and some its cryptographical properties. It has been shown that the probability of the selection of two equivalent keys is very low. Crypto-robustness of this cipher has been evaluated on the basis of its probabilistic model.
Total Spinal Block after Thoracic Paravertebral Block.
Beyaz, Serbülent Gökhan; Özocak, Hande; Ergönenç, Tolga; Erdem, Ali Fuat; Palabıyık, Onur
2014-02-01
Thoracic paravertebral block (TPVB) can be performed with or without general anaesthesia for various surgical procedures. TPVB is a popular anaesthetic technique due to its low side effect profile and high analgesic potency. We used 20 mL of 0.5% levobupivacaine for a single injection of unilateral TPVB at the T7 level with neurostimulator in a 63 year old patient with co-morbid disease who underwent cholecystectomy. Following the application patient lost consciousness, and was intubated. Haemodynamic instability was normalised with rapid volume replacement and vasopressors. Anaesthetic drugs were stopped at the end of the surgery and muscle relaxant was antagonised. Return of mucle strenght was shown with neuromuscular block monitoring. Approximately three hours after TPVB, spontaneous breathing started and consciousness returned. A total spinal block is a rare and life-threatening complication. A total spinal block is a complication of spinal anaesthesia, and it can also occur after peripheral blocks. Clinical presentation is characterised by hypotension, bradicardia, apnea, and cardiac arrest. An early diagnosis and appropriate treatment is life saving. In this case report, we want to present total spinal block after TPVB.
数论、高斯数在密码中的应用%The application of cipher to Gauss number & number theory
郝稚传; 葛建军; 景亚萍
2003-01-01
We have the well-known Pythagoras triple 32+42=52,22+32+62=72.We get Guass number & number theory in appication cipher to formula (1)&(2).={(nm]q)2-2qm{n-1m-1]q*[n-1m]q}2 .and (2){2qm[nm]q*[n-1m]q}2+{2[nm]q*[n-1m-1]q}2+{2qm[n-1m-1]q*[n-1m]q}2={([nm]q)2+(qm[n-1m]q)2+([n-1m-1]q)2}2.[nm]q=∏ni=1(1-qi)/∏mi=1(1-qi)*∏n-mi=1(1-qi).(3)〈(〈(∏ni=1(1-qi)/∏mi=1(1-qi)*∏n-mi=1(1-qi))e〉M)d〉m%我们熟知勾股定理32+42=52,22+32+62=72我们得到两个公式和应用.
Bank Electronic Payment Cipher System%浅谈银行电子支付密码系统实现方案
万鹏; 郑云飞
2013-01-01
With the development of electronic banking and business volume growth, bills fraud cases occur frequently. The traditional method of manual verification of seals and bills has become an obstacle to the develop-ment of banking business. Traditional bill authentication methods have many disadvantages, such as poor security, low efficiency of settlement, with financial risk being difficult to control. To solve these problems, construction of electronic payment cipher system can ensure the safety, efficiency of bill business.%随着银行电子化的发展和业务量的增长，票据诈骗案件频发，传统的手工验证印鉴真伪和票据合法性的方式已经成为制约银行业务发展的障碍。针对传统的票据验证方式防伪能力差、结算效率低、资金风险难以控制等缺点，构建电子支付密码系统可以确保票据业务的安全性和高效性。
Jönsson, Jeppe
2015-01-01
Block tearing is considered in several codes as a pure block tension or a pure block shear failure mechanism. However in many situations the load acts eccentrically and involves the transfer of a substantial moment in combination with the shear force and perhaps a normal force. A literature study...... yield lines around the block leads to simple interaction formulas similar to other interaction formulas in the codes.......Block tearing is considered in several codes as a pure block tension or a pure block shear failure mechanism. However in many situations the load acts eccentrically and involves the transfer of a substantial moment in combination with the shear force and perhaps a normal force. A literature study...
BLOCK H-MATRICES AND SPECTRUM OF BLOCK MATRICES
黄廷祝; 黎稳
2002-01-01
The block H-matrices are studied by the concept of G-functions, several concepts of block matrices are introduced. Equivalent characters of block H-matrices are obtained. Spectrum localizations claracterized by Gfunctions for block matrices are got.
Block TERM factorization of block matrices
SHE Yiyuan; HAO Pengwei
2004-01-01
Reversible integer mapping (or integer transform) is a useful way to realize Iossless coding, and this technique has been used for multi-component image compression in the new international image compression standard JPEG 2000. For any nonsingular linear transform of finite dimension, its integer transform can be implemented by factorizing the transform matrix into 3 triangular elementary reversible matrices (TERMs) or a series of single-row elementary reversible matrices (SERMs). To speed up and parallelize integer transforms, we study block TERM and SERM factorizations in this paper. First, to guarantee flexible scaling manners, the classical determinant (det) is generalized to a matrix function, DET, which is shown to have many important properties analogous to those of det. Then based on DET, a generic block TERM factorization,BLUS, is presented for any nonsingular block matrix. Our conclusions can cover the early optimal point factorizations and provide an efficient way to implement integer transforms for large matrices.
Secure Chaotic Map Based Block Cryptosystem with Application to Camera Sensor Networks
Muhammad Khurram Khan
2011-01-01
Full Text Available Recently, Wang et al. presented an efficient logistic map based block encryption system. The encryption system employs feedback ciphertext to achieve plaintext dependence of sub-keys. Unfortunately, we discovered that their scheme is unable to withstand key stream attack. To improve its security, this paper proposes a novel chaotic map based block cryptosystem. At the same time, a secure architecture for camera sensor network is constructed. The network comprises a set of inexpensive camera sensors to capture the images, a sink node equipped with sufficient computation and storage capabilities and a data processing server. The transmission security between the sink node and the server is gained by utilizing the improved cipher. Both theoretical analysis and simulation results indicate that the improved algorithm can overcome the flaws and maintain all the merits of the original cryptosystem. In addition, computational costs and efficiency of the proposed scheme are encouraging for the practical implementation in the real environment as well as camera sensor network.
Lesson Thirteen Trifascicular Block
鲁端; 王劲
2005-01-01
@@ A complete trifascicular block would result in complete AV block. The idio ventricular rhythm has a slower rate and a wide QRS complex because the pacemaker is located at the peripheral part of the conduction system distal to the sites of the block1. Such a rhythm may be difficult to differentiate from bifascicular or bundle branch block combined with complete block at a higher level such as the AV node or His bundle2. Besides a slower ventricular rate, a change in the morphology of the QRS complex from a previous known bifascicular pattern would be strongly suggestive of a trifascicular origin of the complete AV block3. A His bundle recording is required for a definitive diagnosis, however.
刘伯红; 王刚; 王娟娟; 史慧丽
2014-01-01
To solve the problem of mass data encryption retrieval in the development of cloud storage service ,a new cipher-text data retrieval method is proposed .In this method ,a new retrieval method is designed which use inverted index as the index structure .Firstly ,user inputs the query words and matches on the cipher-text index precisely and transfer the word into other forms and correct the wrong word to query again .And then repeat the above steps under the circumstance if the returned result is lower than the pre-set threshold .This cipher-text data retrieval method improves the privacy of stored data to make users obtain the results what they expect .Finally ,experimental results show that the scheme is effective .%为解决云存储服务海量加密数据检索问题，提出一个新的云存储密文数据检索方法，新方法采用倒排索引结构，首先用户输入检索词，在密文索引中匹配，然后将词转化成其他形式和纠正错误的词之后进行再次查询，在返回结果低于先前设定的临界值的情况下继续执行以上步骤。这种基于云存储的密文数据检索方法提高了存储数据的隐私性，能够使用户得到他们所期望的结果，实验结果证明新的检索方法是有效的。
Ch. Samson
2012-07-01
Full Text Available In this investigation we have developed a procedure for the encryption of an image by applying modern advanced Hill Cipher including a pair of involutory matrices as multiplicands and a set of functions. Firstly we have obtained an encrypted image of a gray level image. Then this analysis is extended to an RGB color image. Here it is interesting to note that the encrypted image of the gray level image and the encrypted image of the color image do not have any resemblance with their corresponding original images. This fact ensures security of images in an effective manner. .
A stream cipher algorithm based on composite chaotic dynamical systems%一种基于复合混沌动力系统的序列密码算法
王丽燕; 李永华; 贾思齐; 刚家泰
2012-01-01
A new stream cipher algorithm is designed based on 2-D Logistic map and piecewise linear chaotic map, which uses the output of 2-D Logistic map as the piecewise parameter P of piecewise linear chaotic map. The encryption algorithm is constructed by piecewise linear chaotic map with P. The simulation experiments and security analyses are conducted for this algorithm, and the random properties and the sensitivity to initial value of stream generated by these two maps are studied. The analytical results of security indicate that this algorithm is effective in encryption, the key, plaintext and cipher text form complex and sensitive nonlinear relations, and the correlation between plaintext and cipher text is very small, which makes the algorithm effectively defend statistic analysis. The leaking of key and plaintext information from cipher text can also be effectively prevented.%基于二维Logistic映射和分段线性混沌映射，提出了一种新的序列密码算法．该算法用二维Logistic映射的输出作为分段线性映射的分段参数P．再用带有参数P的分段线性混沌映射构造加密算法．对算法进行了仿真实验和安全性分析，并对由二维Logistic映射和分段线性混沌映射产生的序列的随机性、初值敏感性等性质进行了研究．安全性分析表明，该算法加密效果良好，密钥、明文与密文之间关系均十分敏感，而且密文和明文的相关度也很小，可以有效地抵御统计分析，防止密文对密钥和明文信息的泄露．
... Blocked Urethral Valves Health Issues Listen Español Text Size Email Print Share Blocked Urethral Valves Page Content Article Body Urine leaves the bladder through a tube called the urethra, which in boys passes through the penis. Rarely, small membranes form across the urethra in ...
Van der Vegt, Wim
2010-01-01
Related Drupal Nodes Block This module exposes a block that uses Latent Semantic Analysis (Lsa) internally to suggest three nodes that are relevant to the node a user is viewing. This module performs three tasks. 1) It periodically indexes a Drupal site and generates a Lsa Term Document Matrix. Inde
... P wave as it normally would. If an electrical signal is blocked before it reaches the ventricles, they won't contract and pump blood to the lungs and the rest of the body. Second-degree heart block is divided into two ...
Van der Vegt, Wim
2010-01-01
Related Drupal Nodes Block This module exposes a block that uses Latent Semantic Analysis (Lsa) internally to suggest three nodes that are relevant to the node a user is viewing. This module performs three tasks. 1) It periodically indexes a Drupal site and generates a Lsa Term Document Matrix. Inde
Arrighi, Pablo
2010-01-01
We define the block neighborhood of a reversible CA, which is related both to its decomposition into a product of block permutations and to quantum computing. We give a purely combinatorial characterization of the block neighborhood, which helps in two ways. First, it makes the computation of the block neighborhood of a given CA relatively easy. Second, it allows us to derive upper bounds on the block neighborhood: for a single CA as function of the classical and inverse neighborhoods, and for the composition of several CAs. One consequence of that is a characterization of a class of "elementary" CAs that cannot be written as the composition of two simpler parts whose neighborhoods and inverse neighborhoods would be reduced by one half.
王丛峰
2015-01-01
本文以互联网金融环境为背景，对电子密码器提出了创新性的设计。并采用在支票上打印二维码的形式对同一票据信息两种不同的验证方式来对比识别，极大地降低了传统票据账务处理潜在的风险，同时也在很大程度上减少了传统支付密码器操作所带来的风险和不准确性。%In this paper, the Internet financial environment is taken as the background, the electronic cipher device is proposed with innovative design. And two different authentication methods of the same billing information are contras⁃tively recognized by adopting the form of printing two-dimensional code in the check, which greatly reduces the po⁃tential risk of traditional bill accounting treatment, also to a large extent reduces the risk and inaccuracy brought by the traditional payment cipher operation.
Satyaki Roy
2012-07-01
Full Text Available In the present paper a new combined cryptographic method called Modified UES Version-I has been introduced. Nath et al. have already developed several symmetric key methods. It combines three different methods namely, Generalized Modified Vernam Cipher method, Permutation method and Columnar Transposition method. Nath et al recently developed few efficient combined encryption methods such as TTJSA, DJMNA where they have used generalized MSA method, NJJSAA method and DJSA methods. Each of the methods can be applied independently to encrypt any message. Nath et. al showed that TTJSA and DJMNA is most suitable methods to encrypt password or any small message. The name of this method is Ultra Encryption Standard modified (UES version-I since it is based on UES version-I developed by Roy et. al. In this method an encryption key pad in Vernam Cipher Method also the feedback has been used which is considered to make the encryption process stronger. Modified UES Version-I may be applied to encrypt data in any office, corporate sectors etc. The method is most suitable to encrypt any type of file such as text, audio, video, image and databases etc
Block copolymer battery separator
Wong, David; Balsara, Nitash Pervez
2016-04-26
The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.
U.S. Environmental Protection Agency — This data layer represents Census 2000 demographic data derived from the PL94-171 redistricting files and SF3. Census geographic entities include blocks, blockgroups...
Stern, Margaret
1987-01-01
Extracts from "Experimenting with Numbers" by Margaret Stern demonstrate the use of Stern Blocks to develop the conceptual base on which learning disabled students can build further mathematical skills. (DB)
Steroidal neuromuscular blocking agents
Wierda, JMKH; Mori, K; Ohmura, A; Toyooka, H; Hatano, Y; Shingu, K; Fukuda, K
1998-01-01
Since 1964 approximately 20 steroidal neuromuscular blocking agents have been evaluated clinically. Pancuronium, a bisquaternary compound designed on the drawingboard, was the first steroidal relaxant introduced into clinical practice worldwide in the 1970's. Although a major improvement, pancuroniu
Block copolymer battery separator
Wong, David; Balsara, Nitash Pervez
2016-04-26
The invention herein described is the use of a block copolymer/homopolymer blend for creating nanoporous materials for transport applications. Specifically, this is demonstrated by using the block copolymer poly(styrene-block-ethylene-block-styrene) (SES) and blending it with homopolymer polystyrene (PS). After blending the polymers, a film is cast, and the film is submerged in tetrahydrofuran, which removes the PS. This creates a nanoporous polymer film, whereby the holes are lined with PS. Control of morphology of the system is achieved by manipulating the amount of PS added and the relative size of the PS added. The porous nature of these films was demonstrated by measuring the ionic conductivity in a traditional battery electrolyte, 1M LiPF.sub.6 in EC/DEC (1:1 v/v) using AC impedance spectroscopy and comparing these results to commercially available battery separators.
Recipient block TMA technique.
Mirlacher, Martina; Simon, Ronald
2010-01-01
New high-throughput screening technologies have led to the identification of hundreds of genes with a potential role in cancer or other diseases. One way to prioritize the leads obtained in such studies is to analyze a large number of tissues for candidate gene expression. The TMA methodology is now an established and frequently used tool for high-throughput tissue analysis. The recipient block technology is the "classical" method of TMA making. In this method, minute cylindrical tissue punches typically measuring 0.6 mm in diameter are removed from donor tissue blocks and are transferred into empty "recipient" paraffin blocks. Up to 1,000 different tissues can be analyzed in one TMA block. The equipment is affordable and easy to use in places where basic skills in histology are available.
Superalloy Lattice Block Structures
Nathal, M. V.; Whittenberger, J. D.; Hebsur, M. G.; Kantzos, P. T.; Krause, D. L.
2004-01-01
Initial investigations of investment cast superalloy lattice block suggest that this technology will yield a low cost approach to utilize the high temperature strength and environmental resistance of superalloys in lightweight, damage tolerant structural configurations. Work to date has demonstrated that relatively large superalloy lattice block panels can be successfully investment cast from both IN-718 and Mar-M247. These castings exhibited mechanical properties consistent with the strength of the same superalloys measured from more conventional castings. The lattice block structure also accommodates significant deformation without failure, and is defect tolerant in fatigue. The potential of lattice block structures opens new opportunities for the use of superalloys in future generations of aircraft applications that demand strength and environmental resistance at elevated temperatures along with low weight.
Multithreaded Encryption and Decryption Technologies of Hyper-Chaos Cipher%基于多线程的超混沌加解密技术
刘硕; 宣蕾
2011-01-01
针对现阶段虚拟机防病毒技术存在的缺陷,本文将基于超混沌Hénon映射的加解密技术与多线程技术相结合,提出了基于多线程超混沌密码的恶意代码隐藏算法；在对恶意代码涉及的隐藏性因素进行分析的基础上,基于层次分析法,提出了恶意代码的隐藏性分析模型.利用灰鸽子这一典型恶意代码对提出的恶意代码隐藏算法进行了实验与测试,并利用隐藏性分析模型对测试结果进行了分析,验证了提出的基于多线程超混沌密码的恶意代码隐藏算法的有效性.本文的研究成果可以增强恶意代码的隐藏性,增加恶意代码的威胁程度,为防病毒技术的发展提供了新思路.%Aiming at the defects of virtual machine antivirus technologies, a hiding algorithm of malicious code based on multithreaded hyper-chaos cipher encryption is proposed by combining hyper-chaos Henon mapping with multithreaded synchronization. Hiddenness factors of malicious code are analyzed, and a hiddenness analysis model of malicious code is proposed based on AHP. Gray pigeon malicious code is used to test and analyze the hiding algorithm of malicious code, and then the hiddenness analysis model of malicious code is used to analyze the experimental results. The results demonstrate the effectiveness of the malicious code hiding algorithm. The research in this paper increases the hiddenness and threat of malicious code, and it provides a new way for antivirus technologies.
Bussink, Barbara E; Holst, Anders Gaarsdal; Jespersen, Lasse
2013-01-01
AimsTo determine the prevalence, predictors of newly acquired, and the prognostic value of right bundle branch block (RBBB) and incomplete RBBB (IRBBB) on a resting 12-lead electrocardiogram in men and women from the general population.Methods and resultsWe followed 18 441 participants included.......5%/2.3% in women, P Right bundle branch block was associated with significantly...... increased all-cause and cardiovascular mortality in both genders with age-adjusted hazard ratios (HR) of 1.31 [95% confidence interval (CI), 1.11-1.54] and 1.87 (95% CI, 1.48-2.36) in the gender pooled analysis with little attenuation after multiple adjustment. Right bundle branch block was associated...
31 CFR 547.302 - Blocked account; blocked property.
2010-07-01
.... 547.302 Section 547.302 Money and Finance: Treasury Regulations Relating to Money and Finance... SANCTIONS REGULATIONS General Definitions § 547.302 Blocked account; blocked property. The terms blocked account and blocked property shall mean any account or property subject to the prohibitions in § 547.201...
... along with the National Institute of Dental and Craniofacial Research (NIDCR) and the National Institute of General Medical Sciences (NIGMS). This finding shows that a specific combination of two molecules can block only pain-related neurons. It holds the promise of major ...
1983-03-01
1967, Cedergren 1974, Federal Highway .’,U .. V,47 -’":: 37 Administration 1980). Block pavements have essentially the same prob- lems with moisture...Vicksburg, Miss. Cedergren , H. R. 1974. Drainage of Highway and Airfield Pavements, John Wiley and Sons, New VOk. I Cement and Concrete Association
Evie Lamtiur
2015-08-01
Full Text Available Young patients with class II skeletal malocclusion are often found. To avoid further discrepancy of this case, myofunctional therapy is one of the options. Functional appliance often used for such treatment. Functional appliance has been modified since activator was introduced by Andresen. With its bulky shape, activator makes difficulty for patient to speak and eat. Patient unable to wear it full time due to uncomfortness and negative facial appearance. In 1977, Clark developed twin block to overcome the weakness of previous appliances. A more simple design allows patient to be more comfortable and willing to wear it longer. Twin block is myofunctional appliance to reposition the mandible forward for skeletal class II correction with retruded mandible. This paper describes the design, clinical management effects of twin block treatment and brief case presentation using twin block appliance. Similar to the study reports found, this case revealed improvement of facial appearance, decrease overjet and overbite, improvement of molar relationship and good compliance of patient.
Contaminated soil concrete blocks
Korte, de A.C.J.; Brouwers, H.J.H.; Limbachiya, Mukesh C.; Kew, Hsein Y.
2009-01-01
According to Dutch law the contaminated soil needs to be remediated or immobilised. The main focus in this article is the design of concrete blocks, containing contaminated soil, that are suitable for large production, financial feasible and meets all technical and environmental requirements. In ord
William R. Veal
1999-09-01
Full Text Available This study examined the effects of a tri-schedule on the academic achievement of students in a high school. The tri-schedule consists of traditional, 4x4 block, and hybrid schedules running at the same time in the same high school. Effectiveness of the schedules was determined from the state mandated test of basic skills in reading, language, and mathematics. Students who were in a particular schedule their freshman year were tested at the beginning of their sophomore year. A statistical ANCOVA test was performed using the schedule types as independent variables and cognitive skill index and GPA as covariates. For reading and language, there was no statistically significant difference in test results. There was a statistical difference mathematics-computation. Block mathematics is an ideal format for obtaining more credits in mathematics, but the block format does little for mathematics achievement and conceptual understanding. The results have content specific implications for schools, administrations, and school boards who are considering block scheduling adoption.
Abdominal wall blocks in adults
Børglum, Jens; Gögenür, Ismail; Bendtsen, Thomas F
2016-01-01
Purpose of review Abdominal wall blocks in adults have evolved much during the last decade; that is, particularly with the introduction of ultrasound-guided (USG) blocks. This review highlights recent advances of block techniques within this field and proposes directions for future research....... Recent findings Ultrasound guidance is now considered the golden standard for abdominal wall blocks in adults, even though some landmark-based blocks are still being investigated. The efficiency of USG transversus abdominis plane blocks in relation to many surgical procedures involving the abdominal wall...... been introduced with success. Future research should also investigate the effect of specific abdominal wall blocks on neuroendocrine and inflammatory stress response after surgery. Summary USG abdominal wall blocks in adults are commonplace techniques today. Most abdominal wall blocks are assigned...
Recovery from blocking between outcomes.
Wheeler, Daniel S; Miller, Ralph R
2005-10-01
Contemporary associative learning research largely focuses on cue competition phenomena that occur when 2 cues are paired with a common outcome. Little research has been conducted to investigate similar phenomena occurring when a single cue is trained with 2 outcomes. Three conditioned lick suppression experiments with rats assessed whether treatments known to alleviate blocking between cues would also attenuate blocking between outcomes. In Experiment 1, conditioned responding recovered from blocking between outcomes when a long retention interval was interposed between training and testing. Experiment 2 obtained recovery from blocking between outcomes when the blocking outcome was extinguished after the blocking treatment. In Experiment 3, a recovery from blocking between outcomes occurred when a reminder stimulus was presented in a novel context prior to testing. Collectively, these studies demonstrate that blocking of outcomes, like blocking of cues, appears to be caused by a deficit in the expression of an acquired association.
SUPERFICIAL CERVICAL PLEXUS BLOCK
Komang Mega Puspadisari
2014-01-01
Full Text Available Superficial cervical plexus block is one of the regional anesthesia in neck were limited to thesuperficial fascia. Anesthesia is used to relieve pain caused either during or after the surgery iscompleted. This technique can be done by landmark or with ultrasound guiding. The midpointof posterior border of the Sternocleidomastoid was identified and the prosedure done on thatplace or on the level of cartilage cricoid.
针对分组密码S盒的能量分析攻击效率研究%The efficiency of power analysis attack based on S-boxes of block ciphers
王丹辉; 王安
2014-01-01
In order to make up the safety assessment of S-boxes,which was traditionally tested by mathematical meth-ods,correlation power analysis and template attack were used on different S-boxes of DES,AES and Serpent. The sim-ulations were put forth by MATLAB to obtain the success rates. The S-box of Serpent was the strongest against both the correlation power analysis and template attack. In correlation power analysis,Serpent needed 206 power traces,while AES and DES needed only 112 and 160 respectively. In addition,AES was stronger than DES against template attack. The results showed that the low-wide S-box was stronger than the high-wide S-box with the same total number of bits in one round.%为弥补数学分析方法对 S 盒安全性评估的不足，使用相关能量分析和模板攻击，对 DES（data encryption standard）、AES（advanced encryption standard）和 Serpent 密码算法中不同的 S 盒结构进行安全评估，使用 MATLAB进行仿真实验。对于相关能量分析，Serpent 算法的单个 S 盒抗攻击性能最强，至少需要206条能量迹，AES 和DES 算法分别需要112条和160条能量迹。对于模板攻击，Serpent 算法的 S 盒也能最有效抵抗模板攻击，而 AES次之，DES 抗攻击性最弱。实验结果表明，在一轮算法操作比特总数相同的情况下，低位宽 S 盒抗能量分析攻击的效果优于高位宽 S 盒。
Cameron, Peter; Scown, Paul; Campbell, Donald
2002-01-01
There is pessimism regarding the ability of the Acute Health Sector to manage access block for emergency and elective patients. Melbourne Health suffered an acute bed crisis in 2001 resulting in record ambulance diversions and emergency department (ED) delays. We conducted an observational study to reduce access block for emergency patients whilst maintaining elective throughput at Melbourne Health. This involved a clinician-led taskforce using previously proven principles for organisational change to implement 51 actions to improve patient access over a three-month period. The primary outcome measures were ambulance diversion, emergency patients waiting more than 12 hours for an inpatient bed, elective throughput and theatre cancellations. Despite a reduction in multi-day bed numbers all primary objectives were met, ambulance diversion decreased to minimal levels, 12-hour waits decreased by 40% and elective throughput was maintained. Theatre cancellations were also minimised. We conclude that access block can be improved by clinician-led implementation of proven process improvements over a short time frame. The ability to sustain change over the longer term requires further study.
E-Block: A Tangible Programming Tool with Graphical Blocks
Danli Wang
2013-01-01
Full Text Available This paper designs a tangible programming tool, E-Block, for children aged 5 to 9 to experience the preliminary understanding of programming by building blocks. With embedded artificial intelligence, the tool defines the programming blocks with the sensors as the input and enables children to write programs to complete the tasks in the computer. The symbol on the programming block's surface is used to help children understanding the function of each block. The sequence information is transferred to computer by microcomputers and then translated into semantic information. The system applies wireless and infrared technologies and provides user with feedbacks on both screen and programming blocks. Preliminary user studies using observation and user interview methods are shown for E-Block's prototype. The test results prove that E-Block is attractive to children and easy to learn and use. The project also highlights potential advantages of using single chip microcomputer (SCM technology to develop tangible programming tools for children.
NSGIC GIS Inventory (aka Ramona) — A polygon feature class of Miami-Dade Census 2000 Blocks. Census blocks are areas bounded on all sides by visible and/or invisible features shown on a map prepared...
NSGIC Local Govt | GIS Inventory — A polygon feature class of Miami-Dade Census 2000 Blocks. Census blocks are areas bounded on all sides by visible and/or invisible features shown on a map prepared...
Ear - blocked at high altitudes
High altitudes and blocked ears; Flying and blocked ears; Eustachian tube dysfunction - high altitude ... eustachian tube is a connection between the middle ear (the space deep to the eardrum) and the ...
Habitat Blocks and Wildlife Corridors
Vermont Center for Geographic Information — Habitat blocks are areas of contiguous forest and other natural habitats that are unfragmented by roads, development, or agriculture. Vermonts habitat blocks are...
Appropriate schemata and building blocks
Yang Haijun; Li Minqiang
2005-01-01
Appropriate schemata as a novel concept to characterize building blocks are introduced, and then, the traits of appropriate schemata are presented. The effects of building blocks by search operators are analyzed. Hence, the experiments on RR-8X8 are employed to verify that appropriate schemata construct the building blocks. The validity of appropriate schemata and building blocks from the views of theory and practice is presented.
Properties of blocked linear systems.
Chen, Weitian; Anderson, Brian D O; Deistler, Manfred; Filler, Alexander
2012-10-01
This paper presents a systematic study on the properties of blocked linear systems that have resulted from blocking discrete-time linear time invariant systems. The main idea is to explore the relationship between the blocked and the unblocked systems. Existing results are reviewed and a number of important new results are derived. Focus is given particularly on the zero properties of the blocked system as no such study has been found in the literature.
Porous block nanofiber composite filters
Ginley, David S.; Curtis, Calvin J.; Miedaner, Alexander; Weiss, Alan J.; Paddock, Arnold
2016-08-09
Porous block nano-fiber composite (110), a filtration system (10) and methods of using the same are disclosed. An exemplary porous block nano-fiber composite (110) includes a porous block (100) having one or more pores (200). The porous block nano-fiber composite (110) also includes a plurality of inorganic nano-fibers (211) formed within at least one of the pores (200).
Property Blocks: Games and Activities.
Humphreys, Alan, Ed.; Dailey, Jean, Ed.
This pamphlet describes the property blocks produced by MINNEMAST, and discusses their use in the development of thinking processes. Classification systems, including block diagrams and tree diagrams, are discussed. Sixteen classroom activities and eleven games which use the blocks are described. Suggestions to the teacher for further reading are…
Niimi, Hirofumi; Koike, Minoru; Takeuchi, Seiichi; Douhara, Noriyoshi
2007-12-01
Humanoid by ROBO-BLOCK (robot block system) and the rational formula of robots were proposed. ROBO-BLOCK is composed of servo motors, the parts for servomotor rotor, the brackets for servomotor fixation, the board parts and the controllers. A robot can be assembled easily by ROBO-BLOCK. Meanwhile, it is convenient when the structure of the robot can be described easily as a character. The whole structure of the robot is expressed as rational formula of the robot to show molecule structure in chemistry. ROBO-BLOCK can be useful for not only the research but also the education. Creative student experiment was done in the college of industrial technology.
Scheler, Fabian; Mitzlaff, Martin; Schröder-Preikschat, Wolfgang
Die Entscheidung, einen zeit- bzw. ereignisgesteuerten Ansatz für ein Echtzeitsystem zu verwenden, ist schwierig und sehr weitreichend. Weitreichend vor allem deshalb, weil diese beiden Ansätze mit äußerst unterschiedlichen Kontrollflussabstraktionen verknüpft sind, die eine spätere Migration zum anderen Paradigma sehr schwer oder gar unmöglich machen. Wir schlagen daher die Verwendung einer Zwischendarstellung vor, die unabhängig von der jeweils verwendeten Kontrollflussabstraktion ist. Für diesen Zweck verwenden wir auf Basisblöcken basierende Atomic Basic Blocks (ABB) und bauen darauf ein Werkzeug, den Real-Time Systems Compiler (RTSC) auf, der die Migration zwischen zeit- und ereignisgesteuerten Systemen unterstützt.
Spintronics: Conceptual Building Blocks
Ansermet, J.-Ph.
The purpose of this introduction to spintronics is to provide some elementary description of its conceptual building blocks. Thus, it is intended for a newcomer to the field. After recalling rudimentary descriptions of spin precession and spin relaxation, spin-dependent transport is treated within the Boltzmann formalism. This suffices to introduce key notions such as the spin asymmetry of the conductivities in the two-current model, the spin diffusion length, and spin accumulation. Two basic mechanisms of spin relaxation are then presented, one arising from spin-orbit scattering and the other from electron-magnon collisions. Finally, the action of a spin-polarized current on magnetization is presented in a thermodynamics framework. This introduces the notion of spin torque and the characteristic length scale over which the transverse spin polarization of conduction electron decays as it is injected into a magnet.
Dorbolo, Stephane; Adami, Nicolas; Grasp Team
2014-11-01
The motion of ice discs released at the surface of a thermalized bath was investigated. As observed in some rare events in the Nature, the discs start spinning spontaneously. The motor of this motion is the cooling of the water close to the ice disc. As the density of water is maximum at 4°C, a downwards flow is generated from the surface of the ice block to the bottom. This flow generates the rotation of the disc. The speed of rotation depends on the mass of the ice disc and on the temperature of the bath. A model has been constructed to study the influence of the temperature of the bath. Finally, ice discs were put on a metallic plate. Again, a spontaneous rotation was observed. FNRS is thanked for financial support.
Akinci, Devrim [Department of Radiology, Hacettepe University School of Medicine, Sihhiye, 06100 Ankara (Turkey); Akhan, Okan [Department of Radiology, Hacettepe University School of Medicine, Sihhiye, 06100 Ankara (Turkey)]. E-mail: oakhan@hacettepe.edu.tr
2005-09-01
Pain occurs frequently in patients with advanced cancers. Tumors originating from upper abdominal viscera such as pancreas, stomach, duodenum, proximal small bowel, liver and biliary tract and from compressing enlarged lymph nodes can cause severe abdominal pain, which do not respond satisfactorily to medical treatment or radiotherapy. Percutaneous celiac ganglia block (CGB) can be performed with high success and low complication rates under imaging guidance to obtain pain relief in patients with upper abdominal malignancies. A significant relationship between pain relief and degree of tumoral celiac ganglia invasion according to CT features was described in the literature. Performing the procedure in the early grades of celiac ganglia invasion on CT can increase the effectiveness of the CGB, which is contrary to World Health Organization criteria stating that CGB must be performed in patients with advanced stage cancer. CGB may also be effectively performed in patients with chronic pancreatitis for pain palliation.
Hanberg, Peter Jesper; Jørgensen, Anders Michael
2014-01-01
it directcompetitive with fossil energy sources a further reduction is needed. By increasing the efficiency of the solar cells one gain an advantage through the whole chain of cost. So that per produced Watt of power less material is spent, installation costs are lower, less area is used etc. With an average...... efficiency of about 15% for commercial Silicon solar cells there is still much to gain. DTU Danchip provides research facilities, equipment and expertise for the building blocks that comprises fabricating the efficient solar cell. In order to get more of the sun light into the device we provide thin film......Photovoltaics (PV), better known as solar cells, are now a common day sight on many rooftops in Denmark.The installed capacity of PV systems worldwide is growing exponentially1 and is the third most importantrenewable energy source today. The cost of PV is decreasing fast with ~10%/year but to make...
李淼; 徐建博
2012-01-01
复合域乘法运算是对称密码算法中的基本运算和重要模块,因操作复杂且计算时间长,其实现性能在很大程度上制约着对称密码算法的运算速度.文章研究了对称密码算法中的复合域乘法运算特点及实现原理,设计了以GF(28)为基域,扩展到GF((28)k)(k=1,2,3,4)域上的复合域乘法可重构架构,通过配置能够灵活高效地实现GF(28)、GF((28)2)、GF((28)3)、GF((28)4)域上的有限域乘法操作.同时结合处理器的指令设计方法,设计了通用的复合域乘法操作及配置指令,能够极大的提高对称密码算法中复合域乘法运算的处理效率.最后文章对复合域乘法可重构架构进行了模拟与验证,在0.18μm CMOS工艺标准单元库下进行逻辑综合以及布局布线,并对综合结果进行了性能评估.结果表明,文章提出的复合域乘法可重构架构及相应的专用指令,在灵活性的前提下提供了较高的执行效率,具有较高的实用价值.% The composite field multiplication is a basic operation and important module in symmetric cipher algorithms. Due to complicated operation and long computation time, the performance of composite field multiplication restricts the computing speed of symmetric cipher algorithms to a large extent. In this paper, the operating characteristics and realization principle of composite field multiplication have been researched, and a reconfigurable architecture of composite field multiplication on GF(28) basic field and extend to GF((28)k)(k=1,2,3,4) extension field has been presented. By configuration, this architecture can implement finite field multiplication operation on GF(28), GF((28)2), GF((28)3) and GF((28)4) flexibly and efficiently. In the meanwhile, combined with instruction design method of general-purpose processors, general composite field multiplication operation and configuration instructions have been designed, which can greatly improve the processing
Lin, W
2001-12-01
This report documents the Large-Block Test (LBT) conducted at Fran Ridge near Yucca Mountain, Nevada. The LBT was a thermal test conducted on an exposed block of middle non-lithophysal Topopah Spring tuff (Tptpmn) and was designed to assist in understanding the thermal-hydrological-mechanical-chemical (THMC) processes associated with heating and then cooling a partially saturated fractured rock mass. The LBT was unique in that it was a large (3 x 3 x 4.5 m) block with top and sides exposed. Because the block was exposed at the surface, boundary conditions on five of the six sides of the block were relatively well known and controlled, making this test both easier to model and easier to monitor. This report presents a detailed description of the test as well as analyses of the data and conclusions drawn from the test. The rock block that was tested during the LBT was exposed by excavation and removal of the surrounding rock. The block was characterized and instrumented, and the sides were sealed and insulated to inhibit moisture and heat loss. Temperature on the top of the block was also controlled. The block was heated for 13 months, during which time temperature, moisture distribution, and deformation were monitored. After the test was completed and the block cooled down, a series of boreholes were drilled, and one of the heater holes was over-cored to collect samples for post-test characterization of mineralogy and mechanical properties. Section 2 provides background on the test. Section 3 lists the test objectives and describes the block site, the site configuration, and measurements made during the test. Section 3 also presents a chronology of events associated with the LBT, characterization of the block, and the pre-heat analyses of the test. Section 4 describes the fracture network contained in the block. Section 5 describes the heating/cooling system used to control the temperature in the block and presents the thermal history of the block during the test
Dimensional Reduction for Conformal Blocks
Hogervorst, Matthijs
2016-01-01
We consider the dimensional reduction of a CFT, breaking multiplets of the d-dimensional conformal group SO(d+1,1) up into multiplets of SO(d,1). This leads to an expansion of d-dimensional conformal blocks in terms of blocks in d-1 dimensions. In particular, we obtain a formula for 3d conformal blocks as an infinite sum over 2F1 hypergeometric functions with closed-form coefficients.
Reliability computation from reliability block diagrams
Chelson, P. O.; Eckstein, E. Y.
1975-01-01
Computer program computes system reliability for very general class of reliability block diagrams. Four factors are considered in calculating probability of system success: active block redundancy, standby block redundancy, partial redundancy, and presence of equivalent blocks in the diagram.
Lorenzo Milazzo
1997-05-01
Full Text Available An ASQS(v is a particular Steiner system featuring a set of v vertices and two separate families of blocks, B and G, whose elements have a respective cardinality of 4 and 6. It has the property that any three vertices of X belong either to a B-block or to a G-block. The parameter cb is the number of common blocks in two separate ASQSs, both defined on the same set of vertices X . In this paper it is shown that cb ≤ 29 for any pair of ASQSs(12.
Eikonalization of Conformal Blocks
Fitzpatrick, A Liam; Walters, Matthew T; Wang, Junpu
2015-01-01
Classical field configurations such as the Coulomb potential and Schwarzschild solution are built from the $t$-channel exchange of many light degrees of freedom. We study the CFT analog of this phenomenon, which we term the `eikonalization' of conformal blocks. We show that when an operator $T$ appears in the OPE $\\mathcal{O}(x) \\mathcal{O}(0)$, then the large spin $\\ell$ Fock space states $[TT \\cdots T]_{\\ell}$ also appear in this OPE with a computable coefficient. The sum over the exchange of these Fock space states in an $\\langle \\mathcal{O} \\mathcal{O} \\mathcal{O} \\mathcal{O} \\rangle$ correlator build the classical `$T$ field' in the dual AdS description. In some limits the sum of all Fock space exchanges can be represented as the exponential of a single $T$ exchange in the 4-pt correlator of $\\mathcal{O}$. Our results should be useful for systematizing $1/\\ell$ perturbation theory in general CFTs and simplifying the computation of large spin OPE coefficients. As examples we obtain the leading $\\log \\ell$...
Adductor Canal Block versus Femoral Nerve Block and Quadriceps Strength
Jæger, Pia Therese; Nielsen, Zbigniew Jerzy Koscielniak; Henningsen, Lene Marianne;
2013-01-01
: The authors hypothesized that the adductor canal block (ACB), a predominant sensory blockade, reduces quadriceps strength compared with placebo (primary endpoint, area under the curve, 0.5-6 h), but less than the femoral nerve block (FNB; secondary endpoint). Other secondary endpoints were...
Knudsen, Lars Ramkilde; Wagner, David
2002-01-01
This paper considers a cryptanalytic approach called integral cryptanalysis. It can be seen as a dual to differential cryptanalysis and applies to ciphers not vulnerable to differential attacks. The method is particularly applicable to block ciphers which use bijective components only.......This paper considers a cryptanalytic approach called integral cryptanalysis. It can be seen as a dual to differential cryptanalysis and applies to ciphers not vulnerable to differential attacks. The method is particularly applicable to block ciphers which use bijective components only....
Design of State Machine for Time-fuzed Initiation Device with Digital Cipher%数字密码定时引爆装置的状态机设计
魏峰; 田红凤; 孙文侠
2011-01-01
设计的数字密码定时引爆装置可以用于炸药定时引爆,在武器系统等军工领域有着广泛的应用.给出了引爆装置设计方案,并设计了引爆装置的核心逻辑部分状态机,仿真结果表明,状态机动作正确.该方案设计的引爆装置可以用CPLD实现,为工业流片奠定了基础.%The time-fuzed initiation device with digital cipher designed can be used for time initition ofexplosive in this paper. The design proposal of the initition device is given;designed the state machine-----key logi part of initition device. The results of simulation indicate that the action of state machine is correct.
Geography:The TIGER Line Files are feature classes and related database files (.) that are an extract of selected geographic and cartographic information from the U.S. Census Bureau's Master Address File / Topologically Integrated Geographic Encoding and Referencing (MAF/TIGER) Database (MTDB). The MTDB represents a seamless national file with no overlaps or gaps between parts, however, each TIGER Line File is designed to stand alone as an independent data set, or they can be combined to cover the entire nation. Census Blocks are statistical areas bounded on all sides by visible features, such as streets, roads, streams, and railroad tracks, and/or by non visible boundaries such as city, town, township, and county limits, and short line-of-sight extensions of streets and roads. Census blocks are relatively small in area; for example, a block in a city bounded by streets. However, census blocks in remote areas are often large and irregular and may even be many square miles in area. A common misunderstanding is that data users think census blocks are used geographically to build all other census geographic areas, rather all other census geographic areas are updated and then used as the primary constraints, along with roads and water features, to delineate the tabulation blocks. As a result, all 2010 Census blocks nest within every other 2010 Census geographic area, so that Census Bureau statistical data can be tabulated at the block level and aggregated up t
Block storage subsystem performance analysis
CERN. Geneva
2016-01-01
You feel that your service is slow because of the storage subsystem? But there are too many abstraction layers between your software and the raw block device for you to debug all this pile... Let's dive on the platters and check out how the block storage sees your I/Os! We can even figure out what those patterns are meaning.
The Effectiveness of Block Scheduling.
Creamean, Sharon Lightle; Horvath, Robert Jeffery
This report describes a program for the exploration of block scheduling. The targeted population consists of high school students in a growing, middle-class community, located in a suburban setting of a large mid-western city. The historical background of block scheduling is documented through data gathered using attendance reports, student…
1977-01-01
The photo shows a four-block collimator installed on a control table for positioning the alignment reference marks. Designed for use with the secondary beams, the collimators operated in vacuum conditions. The blocks were made of steel and had a standard length of 1 m. The maximum aperture had a square coss-section of 144 cm2. (See Annual Report 1976.)
Block Transfer Agreement Evaluation Project
Bastedo, Helena
2010-01-01
The objective of this project is to evaluate for the British Columbia Council on Admissions and Transfer (BCCAT) the effectiveness of block transfer agreements (BTAs) in the BC Transfer System and recommend steps to be taken to improve their effectiveness. Findings of this study revealed that institutions want to expand block credit transfer;…
OPAL Various Lead Glass Blocks
These lead glass blocks were part of a CERN detector called OPAL (one of the four experiments at the LEP particle detector). OPAL uses some 12 000 blocks of glass like this to measure particle energies in the electromagnetic calorimeter. This detector measured the energy deposited when electrons and photons were slowed down and stopped.
The wild tapered block bootstrap
Hounyo, Ulrich
In this paper, a new resampling procedure, called the wild tapered block bootstrap, is introduced as a means of calculating standard errors of estimators and constructing confidence regions for parameters based on dependent heterogeneous data. The method consists in tapering each overlapping block...
Conformal Nets II: Conformal Blocks
Bartels, Arthur; Douglas, Christopher L.; Henriques, André
2017-03-01
Conformal nets provide a mathematical formalism for conformal field theory. Associated to a conformal net with finite index, we give a construction of the `bundle of conformal blocks', a representation of the mapping class groupoid of closed topological surfaces into the category of finite-dimensional projective Hilbert spaces. We also construct infinite-dimensional spaces of conformal blocks for topological surfaces with smooth boundary. We prove that the conformal blocks satisfy a factorization formula for gluing surfaces along circles, and an analogous formula for gluing surfaces along intervals. We use this interval factorization property to give a new proof of the modularity of the category of representations of a conformal net.
Conformal Nets II: Conformal Blocks
Bartels, Arthur; Douglas, Christopher L.; Henriques, André
2017-08-01
Conformal nets provide a mathematical formalism for conformal field theory. Associated to a conformal net with finite index, we give a construction of the `bundle of conformal blocks', a representation of the mapping class groupoid of closed topological surfaces into the category of finite-dimensional projective Hilbert spaces. We also construct infinite-dimensional spaces of conformal blocks for topological surfaces with smooth boundary. We prove that the conformal blocks satisfy a factorization formula for gluing surfaces along circles, and an analogous formula for gluing surfaces along intervals. We use this interval factorization property to give a new proof of the modularity of the category of representations of a conformal net.
Risum, Niels; Strauss, David; Sogaard, Peter
2013-01-01
The relationship between myocardial electrical activation by electrocardiogram (ECG) and mechanical contraction by echocardiography in left bundle-branch block (LBBB) has never been clearly demonstrated. New strict criteria for LBBB based on a fundamental understanding of physiology have recently...
Hawaii Census 2000 Block Groups
U.S. Environmental Protection Agency — This data layer represents Census 2000 demographic data derived from the PL94-171 redistricting files and SF3. Census geographic entities include blocks, blockgroups...
Risum, Niels; Strauss, David; Sogaard, Peter;
2013-01-01
The relationship between myocardial electrical activation by electrocardiogram (ECG) and mechanical contraction by echocardiography in left bundle-branch block (LBBB) has never been clearly demonstrated. New strict criteria for LBBB based on a fundamental understanding of physiology have recently...
Recursion Relations for Conformal Blocks
Penedones, João; Yamazaki, Masahito
2016-09-12
In the context of conformal field theories in general space-time dimension, we find all the possible singularities of the conformal blocks as functions of the scaling dimension $\\Delta$ of the exchanged operator. In particular, we argue, using representation theory of parabolic Verma modules, that in odd spacetime dimension the singularities are only simple poles. We discuss how to use this information to write recursion relations that determine the conformal blocks. We first recover the recursion relation introduced in 1307.6856 for conformal blocks of external scalar operators. We then generalize this recursion relation for the conformal blocks associated to the four point function of three scalar and one vector operator. Finally we specialize to the case in which the vector operator is a conserved current.
Bureau of Ocean Energy Management, Department of the Interior — This data set contains OCS block outlines and delineated polygons in ESRI ArcGIS shape file format for the BOEM Gulf of Mexico Region that contain sediment resources...
Multi-block and path modelling procedures
Høskuldsson, Agnar
2008-01-01
The author has developed a unified theory of path and multi-block modelling of data. The data blocks are arranged in a directional path. Each data block can lead to one or more data blocks. It is assumed that there is given a collection of input data blocks. Each of them is supposed to describe one...
A Novel Tetrathiafulvalene Building Block
Jeppesen, Jan Oskar; Takimiya, Kazuo; Thorup, Niels
1999-01-01
Efficient synthesis of a novel tetrathiafulvalene building block. 2,3-bis(2-cyanoethylthio)-6,7-bis(thiocyanato-methyl)tetrathiafulv alene (7) useful for stepwise and asymmetrical bis-function-alization is reported.......Efficient synthesis of a novel tetrathiafulvalene building block. 2,3-bis(2-cyanoethylthio)-6,7-bis(thiocyanato-methyl)tetrathiafulv alene (7) useful for stepwise and asymmetrical bis-function-alization is reported....
[Superior gluteal nerve: a new block on the block?
Sá, Miguel; Graça, Rita; Reis, Hugo; Cardoso, José Miguel; Sampaio, José; Pinheiro, Célia; Machado, Duarte
2017-05-24
The superior gluteal nerve is responsible for innervating the gluteus medius, gluteus minimus and tensor fascia latae muscles, all of which can be injured during surgical procedures. We describe an ultrasound-guided approach to block the superior gluteal nerve which allowed us to provide efficient analgesia and anesthesia for two orthopedic procedures, in a patient who had significant risk factors for neuraxial techniques and deep peripheral nerve blocks. An 84-year-old female whose regular use of clopidogrel contraindicated neuraxial techniques or deep peripheral nerve blocks presented for urgent bipolar hemiarthroplasty in our hospital. Taking into consideration the surgical approach chosen by the orthopedic team, we set to use a combination of general anesthesia and superficial peripheral nerve blocks (femoral, lateral cutaneous of thigh and superior gluteal nerve) for the procedure. A month and a half post-discharge the patient was re-admitted for debriding and correction of suture dehiscence; we performed the same blocks and light sedation. She remained comfortable in both cases, and reported no pain in the post-operative period. Deep understanding of anatomy and innervation empowers anesthesiologists to solve potentially complex cases with safer, albeit creative, approaches. The relevance of this block in this case arises from its innervation of the gluteus medius muscle and posterolateral portion of the hip joint. To the best of our knowledge, this is the first report of an ultrasound-guided superior gluteal nerve block with an analgesic and anesthetic goal, which was successfully achieved. Copyright © 2016 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.
NANOSTRUCTURES OF FUNCTIONAL BLOCK COPOLYMERS
Guojun Liu
2000-01-01
Nanostructure fabrication from block copolymers in my group normally involves polymer design, synthesis, selfassembly, selective domain crosslinking, and sometimes selective domain removal. Preparation of thin films with nanochannels was used to illustrate the strategy we took. In this particular case, a linear triblock copolymer polyisopreneblock-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate), PI-b-PCEMA-b-PtBA, was used. Films, 25 to50μm thick, were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer,hPtBA, where hPtBA is shorter than the PtBA block. At the hPtBA mass fraction of 20% relative to the triblock or the total PtBA (hPtBA and PtBA block) volume fraction of 0.44, hPtBA and PtBA formed a seemingly continuous phase in the matrix of PCEMA and PI. Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain. Nanochannels were formed by extracting out hPtBA with solvent. Alternatively, larger channels were obtained from extracting out hPtBA and hydrolyzing the t-butyl groups of the PtBA block. Such membranes were not liquid permeable but had gas permeability constants ～6 orders of magnitude higher than that of low-density polyethylene films.
支持密文索引的数据库透明加密方法%A Method of Transparently Encrypting Database Data Supporting Cipher-text Index
朱继锋; 戴林; 杜顶; 李鹏辉; 段晶晶
2011-01-01
随着数据库的应用日益广泛,如何保护隐私数据和防止敏感数据泄露成为当前面临的重大挑战。数据库加密被证明是保护数据安全的有效手段,但是对数据库进行加密之后,数据之间原有的偏序关系将会丧失,无法通过原来的索引机制来加快对密文数据的条件查询。本文提出一种对数据库中的字段进行透明加密并实现高效条件查询的方法,并报告了基于该方法开发的数据库加密系统的测试数据。%As the database is applied widely,a critical challenge is to preserve data privacy and prevent sensitive information from disclosure.The database encryption technology has been proven an effective method to preserve data security.However,as the original partially ordered relationship of database data would be lost while the database is encrypted,it is impossible to quicken the conditional query on the cipher-text data.This paper proposes a new method of transparently encryption of records,which supports conditional query on encrypted database data.Experimental results of a database-encryption system designed based on this method are reported.
Zhaolin Jiang
2014-01-01
Full Text Available We first give the block style spectral decomposition of arbitrary block skew circulant matrix with skew circulant blocks. Secondly, we obtain the singular value of block skew circulant matrix with skew circulant blocks as well. Finally, based on the block style spectral decomposition, we deal with the optimal backward perturbation analysis for the block skew circulant linear system with skew circulant blocks.
Contrasting reduced overshadowing and blocking.
Wheeler, Daniel S; Miller, Ralph R
2007-07-01
Preexposure of a cue without an outcome (X-) prior to compound pairings with the outcome (XZ-->O) can reduce overshadowing of a target cue (Z). Moreover, pairing a cue with an outcome (X-->O) before compound training can enhance its ability to compete with another cue (i.e., blocking). Four experiments were conducted in a conditioned bar-press suppression preparation with rats to determine whether spacing of the X- or X-->O trials would differentially affect reduced overshadowing and blocking. Experiment 1a showed that reduced overshadowing was larger with massed trials than with spaced trials. Experiment 1b found that blocking was larger with spaced trials than with massed trials. Experiments 2a and 2b indicated that these effects of trial spacing were both mediated by the associative status of the context at test. The results are interpreted in the framework of contemporary learning theories.
Diversity Gain through Antenna Blocking
V. Dehghanian
2012-01-01
Full Text Available As part of the typical usage mode, interaction between a handheld receiver antenna and the operator's RF absorbing body and nearby objects is known to generate variability in antenna radiation characteristics through blocking and pattern changes. It is counterintuitive that random variations in blocking can result in diversity gain of practical applicability. This diversity gain is quantified from a theoretical and experimental perspective. Measurements carried out at 1947.5 MHz verify the theoretical predictions, and a diversity gain of 3.1 dB was measured through antenna blocking and based on the utilized measurement setup. The diversity gain can be exploited to enhance signal detectability of handheld receivers based on a single antenna in indoor multipath environments.
Block ground interaction of rockfalls
Volkwein, Axel; Gerber, Werner; Kummer, Peter
2016-04-01
During a rockfall the interaction of the falling block with the ground is one of the most important factors that define the evolution of a rockfall trajectory. It steers the rebound, the rotational movement, possibly brake effects, friction losses and damping effects. Therefore, if most reliable rockfall /trajectory simulation software is sought a good understanding of the block ground interaction is necessary. Today's rockfall codes enable the simulation of a fully 3D modelled block within a full 3D surface . However, the details during the contact, i.e. the contact duration, the penetration depth or the dimension of the marks in the ground are usually not part of the simulation. Recent field tests with rocks between 20 and 80 kg have been conducted on a grassy slope in 2014 [1]. A special rockfall sensor [2] within the blocks measured the rotational velocity and the acting accelerations during the tests. External video records and a so-called LocalPositioningSystem deliver information on the travel velocity. With these data not only the flight phases of the trajectories but also the contacts with the ground can be analysed. During the single jumps of a block the flight time, jump length, the velocity, and the rotation are known. During the single impacts their duration and the acting accelerations are visible. Further, the changes of rotational and translational velocity influence the next jump of the block. The change of the rotational velocity over the whole trajectory nicely visualizes the different phases of a rockfall regarding general acceleration and deceleration in respect to the inclination and the topography of the field. References: [1] Volkwein A, Krummenacher B, Gerber W, Lardon J, Gees F, Brügger L, Ott T (2015) Repeated controlled rockfall trajectory testing. [Abstract] Geophys. Res. Abstr. 17: EGU2015-9779. [2] Volkwein A, Klette J (2014) Semi-Automatic Determination of Rockfall Trajectories. Sensors 14: 18187-18210.
This array of 96 lead glass bricks formed part of the OPAL electromagnetic calorimeter. One half of the complete calorimeter is shown in the picture above. There were 9440 lead glass counters in the OPAL electromagnetic calorimeter. These are made of Schott type SF57 glass and each block weighs about 25 kg and consists of 76% PbO by weight. Each block has a Hamamatsu R2238 photomultiplier glued on to it. The complete detector was in the form of a cylinder 7m long and 6m in diameter. It was used to measure the energy of electrons and photons produced in LEP interactions.
Maloney, Alexander; Maxfield, Henry; Ng, Gim Seng
2017-06-01
We investigate the constraints of crossing symmetry on CFT correlation functions. Four point conformal blocks are naturally viewed as functions on the upper-half plane, on which crossing symmetry acts by PSL(2, Z ) modular transformations. This allows us to construct a unique, crossing symmetric function out of a given conformal block by averaging over PSL(2, Z ). In some two dimensional CFTs the correlation functions are precisely equal to the modular average of the contributions of a finite number of light states. For example, in the two dimensional Ising and tri-critical Ising model CFTs, the correlation functions of identical operators are equal to the PSL(2, Z ) average of the Virasoro vacuum block; this determines the 3 point function coefficients uniquely in terms of the central charge. The sum over PSL(2, Z ) in CFT2 has a natural AdS3 interpretation as a sum over semi-classical saddle points, which describe particles propagating along rational tangles in the bulk. We demonstrate this explicitly for the correlation function of certain heavy operators, where we compute holographically the semi-classical conformal block with a heavy internal operator.
Vagal Blocking for Obesity Control
Johannessen, Helene; Revesz, David; Kodama, Yosuke
2017-01-01
BACKGROUND: Recently, the US FDA has approved "vagal blocking therapy or vBLoc® therapy" as a new treatment for obesity. The aim of the present study was to study the mechanism-of-action of "VBLOC" in rat models. METHODS: Rats were implanted with VBLOC, an intra-abdominal electrical device...
Scattering matrices with block symmetries
Życzkowski, Karol
1997-01-01
Scattering matrices with block symmetry, which corresponds to scattering process on cavities with geometrical symmetry, are analyzed. The distribution of transmission coefficient is computed for different number of channels in the case of a system with or without the time reversal invariance. An interpolating formula for the case of gradual time reversal symmetry breaking is proposed.
Architectures for block Toeplitz systems
Bouras, Ilias; Glentis, George-Othon; Kalouptsidis, Nicholas
1996-01-01
In this paper efficient VLSI architectures of highly concurrent algorithms for the solution of block linear systems with Toeplitz or near-to-Toeplitz entries are presented. The main features of the proposed scheme are the use of scalar only operations, multiplications/divisions and additions, and th
Enduring and Diagnosing Reader's Block.
Melanson, Lisa Stapleton
1990-01-01
Describes a condition called "reader's block" whereby the mind fails to comprehend the meaning of the text because of digressing thoughts. Suggests that "freereading," like freewriting, can help to clarify thoughts. Argues that it is not necessary to read things correctly the first time through. (PRA)
First Degree Pacemaker Exit Block
Johnson Francis
2016-10-01
Full Text Available Usually atrial and ventricular depolarizations follow soon after the pacemaker stimulus (spike on the ECG. But there can be an exit block due to fibrosis at the electrode - tissue interface at the lead tip. This can increase the delay between the spike and atrial or ventricular depolarization.
Building Blocks for Personal Brands
Thomas, Lisa Carlucci
2011-01-01
In this article, the author discusses the four essential building blocks for personal brands: (1) name; (2) message; (3) channels; and (4) bridges. However, outstanding building materials can only take a person so far. The author emphasizes that vision, determination, faith, a sense of humor, and humility are also required.
王红胜; 徐子言; 张阳; 陈开颜; 李宝晨; 吴令安
2016-01-01
The security of information transmission is of paramount importance in all sectors of society, whether civilian or defence related. In ancient times the encryption of secret messages was mainly realized by physical or chemical means, but this was later supplemented by mathematical techniques. In parallel, the breaking of enemy codes has also been a subject of intense study. To date, the only known absolutely secure means of encryption is through quantum cryp-tography. However, this still has to be implemented by equipment that is vulnerable to various physical attacks, so it is important to study these methods of attack, both for legitimate users and for the surveillance of criminal activities. Today, nearly all transactions have to be realized through the computer and much effort has been devoted to cracking the software. However, little attention has been paid to the hardware, and it has only recently been realized that computer chips themselves can leak sensitive information, from which a code may even be deciphered. By studying the photonic emission and the data dependency of a cryptographic chip during operation, the corre-spondence between the Hamming weight of the operand and the number of photons emitted may be established, based on which a simple and effective method is proposed to crack the Advanced Encryption Standard (AES) cipher chip. An experimental platform has been set up for measuring and analyzing the leaked photonic emission using time-correlated single-photon counting. An AT89C52 microcontroller implementing the operation of the AES cipher algorithm is used as a cipher chip. The emitted photons are collected when the first AddRoundKey and SubBytes of the AES encryption arithmetic are executed, and their respective numbers are found to have a linear relationship with the operand Hamming weight. The sources of noise affecting the photon emission trace have been analyzed, so that the measurement error and uncertainty can be reduced effectively
Endoscopic sphenopalatine ganglion block for pain relief
Murty, P. S. N.; Prasanna, Atma
1998-01-01
The anaesthetic effect of the sphenopalatine (SPG) block has been well utilized for intranasal topical anaesthesia but the analgesic efficacy of (SPG) block, though well documented in literature, has not been put into practice. The methods available for SPG block till date were blind as they do not visualize the foramen. Nasal endoscopies have been used to visualize the foramen for an effective block. The authors present their experience with the endoscopic sphenopalatine ganglion block for p...
Pourfour Du Petit syndrome after interscalene block
Mysore Chandramouli Basappji Santhosh
2013-01-01
Full Text Available Interscalene block is commonly associated with reversible ipsilateral phrenic nerve block, recurrent laryngeal nerve block, and cervical sympathetic plexus block, presenting as Horner′s syndrome. We report a very rare Pourfour Du Petit syndrome which has a clinical presentation opposite to that of Horner′s syndrome in a 24-year-old male who was given interscalene block for open reduction and internal fixation of fracture upper third shaft of left humerus.
Pourfour Du Petit syndrome after interscalene block.
Santhosh, Mysore Chandramouli Basappji; Pai, Rohini B; Rao, Raghavendra P
2013-04-01
Interscalene block is commonly associated with reversible ipsilateral phrenic nerve block, recurrent laryngeal nerve block, and cervical sympathetic plexus block, presenting as Horner's syndrome. We report a very rare Pourfour Du Petit syndrome which has a clinical presentation opposite to that of Horner's syndrome in a 24-year-old male who was given interscalene block for open reduction and internal fixation of fracture upper third shaft of left humerus.
Limiting Spectral Distribution of Block Matrices with Toeplitz Block Structure
Basu, Riddhipratim; Ganguly, Shirshendu; Hazra, Rajat Subhra
2011-01-01
We study two specific symmetric random block Toeplitz (of dimension $k \\times k$) matrices: where the blocks (of size $n \\times n$) are (i) matrices with i.i.d. entries, and (ii) asymmetric Toeplitz matrices. Under suitable assumptions on the entries, their limiting spectral distributions (LSDs) exist (after scaling by $\\sqrt{nk}$) when (a) $k$ is fixed and $n \\to\\infty$ (b) $n$ is fixed and $k\\rightarrow \\infty$ (c) $n$ and $k$ go to $\\infty$ simultaneously. Further the LSD's obtained in (a) and (b) coincide with those in (c) when $n$ or respectively $k$ tends to infinity. This limit in (c) is the semicircle law in case (i). In Case (ii) the limit is related to the limit of the random symmetric Toepiltz matrix as obtained by Bryc et al.(2006) and Hammond and Miller(2005).
陈开颜; 余浩; 邹程; 吴恒旭
2013-01-01
为探究现场可编程门阵列（FPGA）密码芯片运行时电磁辐射造成的涉密信息泄漏情况，研究了互补金属氧化物半导体（CMOS）电路直接电磁辐射的原理，构建了FPGA密码芯片的近场电磁辐射模型。根据这个模型，探讨了近场电磁辐射测量点的选取，采用电磁扫描的方法解决了电磁探头在FPGA表面电磁信号采集的定位问题。此外，在阐释了差分电磁分析（DEMA）攻击原理的同时，完成了高级加密标准（AES）的FPGA电路设计，针对FPGA密码系统的DEMA攻击实验表明，通过电磁扫描找到最佳测量点，在42000个样本的条件下能成功破解AES密码电路的128 bit密钥。%To do research for physical information leaked by Electromagnetic(EM)radiations from Field Programmable Gate Arrays(FPGA)cipher chip during its operation, this paper analyzes the principle of direct electromagnetic emanations for Com-plementary Metal-Oxide-Semiconductor(CMOS)circuit, and then a near-field leakage model about FPGA is designed. According to this model, the technique, EM scanning, is used to tackle the problem of the localization of the spatial position of the crypto-processor, in putting an electricmagnetic near-field sensor above the chip. Moreover, Advanced Encryption Standard(AES)circuit is completed based on FPGA cryptosystem and Differential ElectroMagnetic Analysis(DEMA)is introduced. As a result, practical experiment has shown that an attacker can extract the secret 128-bit key using 42000 traces of AES cryptographic device under the condition of having localized the optimal leaking spots characterized by mostly data-dependent EM emissions.
基于两个离散混沌动力系统的序列密码算法%A stream cipher algorithm based on two discrete chaotic dynamical systems
王丽燕; 许佳佳; 李海燕
2014-01-01
A new stream cipher algorithm is designed based on two discrete chaotic dynamical systems.The algorithm uses the front output of the piecewise nonlinear map as the next input of the piecewise nonlinear map,and the iterative sequences are transformed into 0-1 sequence with discrete operator,and then,the 0-1 sequence is used to select the piecewise nonlinear maps of the two chaotic dynamical systems.The simulation test and security analysis are conducted to study the randomness, the initial value sensitivity and other properties of sequences generated by the map.The experimental results show that the algorithm has the characteristics of the high sensitivity of secret key,plaintext and ciphertext,and the small correlation between ciphertext and plaintext.These peculiarities can efficiently prevent ciphertext to leak the information of secret key and plaintext.%基于两个离散混沌动力系统提出了一种新的序列密码算法。该算法用分段非线性映射的上一次迭代的输出作为分段非线性映射的下一次迭代的输入，并将迭代序列通过离散化算子转化为0-1序列，由0-1序列来选择两个混沌动力系统中的分段非线性映射。对算法进行了仿真实验和安全性分析，并对该映射产生的序列的随机性、初始值敏感性及其他性质进行了研究。研究结果表明，算法呈现出密钥、明文与密文之间高度的敏感性，密文和明文之间的相关度极小等特点，从而起到有效防止密文对密钥和明文信息泄露的作用。
On the Eigenvalues and Eigenvectors of Block Triangular Preconditioned Block Matrices
Pestana, Jennifer
2014-01-01
Block lower triangular matrices and block upper triangular matrices are popular preconditioners for 2×2 block matrices. In this note we show that a block lower triangular preconditioner gives the same spectrum as a block upper triangular preconditioner and that the eigenvectors of the two preconditioned matrices are related. © 2014 Society for Industrial and Applied Mathematics.
Graphs obtained from collections of blocks
Colton Magnant
2015-03-01
Full Text Available Given a collection of $d$-dimensional rectangular solids called blocks, no two of which sharing interior points, construct a block graph by adding a vertex for each block and an edge if the faces of the two corresponding blocks intersect nontrivially. It is known that if $d \\geq 3$, such block graphs can have arbitrarily large chromatic number. We prove that the chromatic number can be bounded with only a mild restriction on the sizes of the blocks. We also show that block graphs of block configurations arising from partitions of $d$-dimensional hypercubes into sub-hypercubes are at least $d$-connected. Bounds on the diameter and the hamiltonicity of such block graphs are also discussed.
Maloney, Alexander; Ng, Gim Seng
2016-01-01
We investigate the constraints of crossing symmetry on CFT correlation functions. Four point conformal blocks are naturally viewed as functions on the upper-half plane, on which crossing symmetry acts by PSL(2,Z) modular transformations. This allows us to construct a unique, crossing symmetric function out of a given conformal block by averaging over PSL(2,Z). In some two dimensional CFTs the correlation functions are precisely equal to the modular average of the contributions of a finite number of light states. For example, in the two dimensional Ising and tri-critical Ising model CFTs, the correlation functions of identical operators are equal to the PSL(2,Z) average of the Virasoro vacuum block; this determines the 3 point function coefficients uniquely in terms of the central charge. The sum over PSL(2,Z) in CFT2 has a natural AdS3 interpretation as a sum over semi-classical saddle points, which describe particles propagating along rational tangles in the bulk. We demonstrate this explicitly for the corre...
Hillslope-derived blocks retard river incision
Shobe, Charles M.; Tucker, Gregory E.; Anderson, Robert S.
2016-05-01
The most common detachment-limited river incision models ignore the effects of sediment on fluvial erosion, yet steep reaches of mountain rivers often host clusters of large (>1 m) blocks. We argue that this distribution of blocks is a manifestation of an autogenic negative feedback in which fast vertical river incision steepens adjacent hillslopes, which deliver blocks to the channel. Blocks inhibit incision by shielding the bed and enhancing form drag. We explore this feedback with a 1-D channel-reach model in which block delivery by hillslopes depends on the river incision rate. Results indicate that incision-dependent block delivery can explain the block distribution in Boulder Creek, Colorado. The proposed negative feedback may significantly slow knickpoint retreat, channel adjustment, and landscape response compared to rates predicted by current theory. The influence of hillslope-derived blocks may complicate efforts to extract base level histories from river profiles.
Demographic Data - MDC_BlockGroup
NSGIC Local Govt | GIS Inventory — A polygon feature class of Miami-Dade County Census 2000 Block Groups. A census Block Group is a statistical subdivision of a census Tract consisting of a cluster of...
Demographic Data - MDC_BlockGroup
NSGIC GIS Inventory (aka Ramona) — A polygon feature class of Miami-Dade County Census 2000 Block Groups. A census Block Group is a statistical subdivision of a census Tract consisting of a cluster...
Slickenside developed in chert block
Ando, J.; Hayasaka, Y.; Nishiwaki, T.
2011-12-01
We observe the microstructures of slickenside developed in chert block mainly with a TEM, in order to clarify generation mechanism of the slickenside. This chert block occurs in the Jurassic accretionary complex in eastern Yamaguchi Prefecture, Japan. The complex, chaotic sediment, is composed of allochthonous blocks, mainly of chert, limestone, sandstone and mudstone in the argillaceous matrix. The color of the undeformed chert is pale blue to white, while the surface of slickenside is black. The stereo microscopy indicates the top surface of slickenside is covered with a transparent material, whose composition is mainly Si, measured by EPMA. The striation is well developed on the transparent-Si-material. We made thin sections, parallel and perpendicular to striation and slickenside, respectively. On the thin sections, the elongated quartz grains are oriented obliquely to the slickenside with 20-30 degree. Many fluid inclusions, which represent healed microcracks, are observed within the quartz grains. These quartz grains show strong undulose extinction and bulging-recrystallization. Apatite grains are also observed as a main constituent mineral. We made TEM foils from the above thin section by FIB. TEM observation indicates the amorphous layer with several ten nanometers in width distributes along the slickenside. (We speculate the most part of the amorphous layer are taken away during polishing of the thin section, because the strength of the amorphous layer is weak. Therefore we now make thin section again with care.) The tangled dislocations are developed within the quartz grains. They make subgrains with ca. 1 micrometer in size. These results suggest the slickenside was generated by the frictional melting of quartz grains on slip plane under very high stress condition, same as pseudotachylyte.
Practical Binary Adaptive Block Coder
Reznik, Yuriy A
2007-01-01
This paper describes design of a low-complexity algorithm for adaptive encoding/ decoding of binary sequences produced by memoryless sources. The algorithm implements universal block codes constructed for a set of contexts identified by the numbers of non-zero bits in previous bits in a sequence. We derive a precise formula for asymptotic redundancy of such codes, which refines previous well-known estimate by Krichevsky and Trofimov, and provide experimental verification of this result. In our experimental study we also compare our implementation with existing binary adaptive encoders, such as JBIG's Q-coder, and MPEG AVC (ITU-T H.264)'s CABAC algorithms.
Writer's block in a Chinese sample.
Lee, Sy-Ying; Krashen, Stephen
2003-10-01
To assess whether writer's block occurs in languages other than English, a Chinese language translation of Rose's Writer's Block questionnaire was administered to 98 university students in Taiwan. Analysis suggests that writer's block occurs for Chinese students, and, as in English, it is related to premature editing and to a lack of strategies for dealing with complex writing tasks.
Micellization and Dynamics of a Block Copolymer
Hvidt, Søren
2006-01-01
Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are industrially important copolymers often called Pluronics or Poloxamers. EPE copolymers form micelles with a core of P blocks and different micellar shapes depending on block leng...
Micellization and Dynamics of a Block Copolymer
Hvidt, Søren
2006-01-01
Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are industrially important copolymers often called Pluronics or Poloxamers. EPE copolymers form micelles with a core of P blocks and different micellar shapes depending on block length...
New Considerations of Turbo Block Codes
YUEDianwu; EdSHWEDYK
2004-01-01
It is shown that (1) a general linear systematic block code can be expressed as a turbo block code and therefore can be decoded using any turbo decoding algorithm; (2) a turbo block code can be also encoded and decoded without any interleaver with the same performance as when an interleaver is present.
Støving, Kion; Rothe, Christian; Rosenstock, Charlotte V
2015-01-01
into a medial and lateral part by a vertical line through the anterior superior iliac spine. We measured muscle thickness of the 3 lateral abdominal muscle layers with ultrasound in the relaxed state and during maximal voluntary muscle contraction. The volunteers reported the duration of the sensory block...... and the abdominal muscle-relaxing effect. RESULTS: The lateral part of the cutaneous sensory block area was a median of 266 cm2 (interquartile range, 191-310 cm2) and the medial part 76 cm 2(interquartile range, 54-127 cm2). In all the volunteers, lateral wall muscle thickness decreased significantly by 9.2 mm (6......BACKGROUND AND OBJECTIVES: The transversus abdominis plane (TAP) block is a widely used nerve block. However, basic block characteristics are poorly described. The purpose of this study was to assess the cutaneous sensory block area, muscle-relaxing effect, and block duration. METHODS: Sixteen...
Seismicity of the Jalisco Block
Nunez-Cornu, F. J.; Rutz, M.; Camarena-Garcia, M.; Trejo-Gomez, E.; Reyes-Davila, G.; Suarez-Plascencia, C.
2002-12-01
In April 2002 began to transmit the stations of the first phase of Jalisco Telemetric Network located at the northwest of Jalisco Block and at the area of Volcan de Fuego (Colima Volcano), in June were deployed four additional MarsLite portable stations in the Bahia de Banderas area, and by the end of August one more portable station at Ceboruco Volcano. The data of these stations jointly with the data from RESCO (Colima Telemetric Network) give us the minimum seismic stations coverage to initiate in a systematic and permanent way the study of the seismicity in this very complex tectonic region. A preliminary analysis of seismicity based on the events registered by the networks using a shutter algorithm, confirms several important features proposed by microseismicity studies carried out between 1996 and 1998. A high level of seismicity inside and below of Rivera plate is observed, this fact suggest a very complex stress pattern acting on this plate. Shallow seismicity at south and east of Bahia de Banderas also suggest a complex stress pattern in this region of the Jalisco Block, events at more than 30 km depth are located under the mouth of the bay and in face of it, a feature denominated Banderas Boundary mark the change of the seismic regime at north of this latitude (20.75°N), however some shallow events were located at the region of Nayarit.
Isostatic compression of buffer blocks. Middle scale
Ritola, J.; Pyy, E. [VTT Technical Research Centre of Finland, Espoo (Finland)
2012-01-15
Manufacturing of buffer components using isostatic compression method has been studied in small scale in 2008 (Laaksonen 2010). These tests included manufacturing of buffer blocks using different bentonite materials and different compression pressures. Isostatic mould technology was also tested, along with different methods to fill the mould, such as vibration and partial vacuum, as well as a stepwise compression of the blocks. The development of manufacturing techniques has continued with small-scale (30 %) blocks (diameter 600 mm) in 2009. This was done in a separate project: Isostatic compression, manufacturing and testing of small scale (D = 600 mm) buffer blocks. The research on the isostatic compression method continued in 2010 in a project aimed to test and examine the isostatic manufacturing process of buffer blocks at 70 % scale (block diameter 1200 to 1300 mm), and the aim was to continue in 2011 with full-scale blocks (diameter 1700 mm). A total of nine bentonite blocks were manufactured at 70 % scale, of which four were ring-shaped and the rest were cylindrical. It is currently not possible to manufacture full-scale blocks, because there is no sufficiently large isostatic press available. However, such a compression unit is expected to be possible to use in the near future. The test results of bentonite blocks, produced with an isostatic pressing method at different presses and at different sizes, suggest that the technical characteristics, for example bulk density and strength values, are somewhat independent of the size of the block, and that the blocks have fairly homogenous characteristics. Water content and compression pressure are the two most important properties determining the characteristics of the compressed blocks. By adjusting these two properties it is fairly easy to produce blocks at a desired density. The commonly used compression pressure in the manufacturing of bentonite blocks is 100 MPa, which compresses bentonite to approximately
Understanding and applying cryptography and data security
Elbirt, Adam J
2009-01-01
Introduction A Brief History of Cryptography and Data Security Cryptography and Data Security in the Modern World Existing Texts Book Organization Symmetric-Key Cryptography Cryptosystem Overview The Modulo Operator Greatest Common Divisor The Ring ZmHomework ProblemsSymmetric-Key Cryptography: Substitution Ciphers Basic Cryptanalysis Shift Ciphers Affine Ciphers Homework ProblemsSymmetric-Key Cryptography: Stream Ciphers Random Numbers The One-Time Pad Key Stream GeneratorsReal-World ApplicationsHomework ProblemsSymmetric-Key Cryptography: Block Ciphers The Data Encryption StandardThe Advance
System Synthesis for Networks of Programmable Blocks
Mannion, Ryan; Cotterell, Susan; Vahid, Frank
2011-01-01
The advent of sensor networks presents untapped opportunities for synthesis. We examine the problem of synthesis of behavioral specifications into networks of programmable sensor blocks. The particular behavioral specification we consider is an intuitive user-created network diagram of sensor blocks, each block having a pre-defined combinational or sequential behavior. We synthesize this specification to a new network that utilizes a minimum number of programmable blocks in place of the pre-defined blocks, thus reducing network size and hence network cost and power. We focus on the main task of this synthesis problem, namely partitioning pre-defined blocks onto a minimum number of programmable blocks, introducing the efficient but effective PareDown decomposition algorithm for the task. We describe the synthesis and simulation tools we developed. We provide results showing excellent network size reductions through such synthesis, and significant speedups of our algorithm over exhaustive search while obtaining...
Strengthening Crypto-1 Cipher Against Algebraic Attacks
Farah Afianti
2015-08-01
Full Text Available In the last few years, several studies addressed the problem of data security in Mifare Classic. One of its weaknesses is the low random number quality. This causes SAT solver attacks to have lower complexity. In order to strengthen Crypto-1 against SAT solver attacks, a modification of the feedback function with better cryptographic properties is proposed. It applies a primitive polynomial companion matrix. SAT solvers cannot directly attack the feedback shift register that uses the modified Boolean feedback function, the register has to be split into smaller groups. Experimental testing showed that the amount of memory and CPU time needed were highest when attacking the modified Crypto-1 using the modified feedback function and the original filter function. In addition, another modified Crypto-1, using the modified feedback function and a modified filter function, had the lowest percentage of revealed variables. It can be concluded that the security strength and performance of the modified Crypto-1 using the modified feedback function and the modified filter function are better than those of the original Crypto-1.
The Vigenere Cipher with the TI-83
Hamilton, Michael; Yankosky, Bill
2004-01-01
Cryptology, the science of secret writing, is a great way to introduce students to different areas of mathematics such as number theory, linear algebra, probability and statistics. Cryptology consists of two branches: cryptography and cryptanalysis. Cryptography is the science of designing techniques for encrypting and decrypting a message.…
Applied algebra codes, ciphers and discrete algorithms
Hardy, Darel W; Walker, Carol L
2009-01-01
This book attempts to show the power of algebra in a relatively simple setting.-Mathematical Reviews, 2010… The book supports learning by doing. In each section we can find many examples which clarify the mathematics introduced in the section and each section is followed by a series of exercises of which approximately half are solved in the end of the book. Additional the book comes with a CD-ROM containing an interactive version of the book powered by the computer algebra system Scientific Notebook. … the mathematics in the book are developed as needed and the focus of the book lies clearly o
General Floorplans with L/T-Shaped Blocks Using Corner Block List
Yu-Chun Ma; Xian-Long Hong; She-Qin Dong; C.K.Cheng; Jun Gu
2006-01-01
With the recent advent of deep submicron technology and new packing schemes, the components in the integrated circuit are often not rectangular. On the basis of the representation of Corner Block List (CBL), we propose a new method of handling rectilinear blocks. In this paper, the handling of the rectilinear blocks is simplified by transforming the L/T-shaped block problem into the align-abutment constraint problem. We devise the block rejoining process and block alignment operation for forming the L/T-shaped blocks into their original configurations. The shape flexibility of the soft blocks, and the rotation and reflection of L/T-shaped blocks are exploited to obtain a tight packing. The empty rooms are introduced to the process of block rejoining. The efficiency and effectiveness of the proposed method are demonstrated by the experimental results on a set of some benchmark examples.
[Ultrasound for peripheral neural block].
Kefalianakis, F
2005-03-01
Ultrasound is well established in medicine. Unfortunately, ultrasound is still rarely used in the area of anesthesia. The purpose of the article is to illustrate the possibilities and limitations of ultrasound in regional anesthesia. The basic principles of ultrasound are the piezoelectric effect and the behaviour of acoustic waveforms in human tissue. Ultrasound imaging in medicine uses high frequency pulses of sound waves (2.5-10 MHz). The following images are built up from the reflected sounds. The ultrasound devices used in regional anesthesia (commonly by 10 MHz) deliver a two-dimensional view. The main step for a successful regional anaesthesia is to identify the exact position of the nerve. In addition, specific surface landmarks and the use of peripheral nerve stimulator help to detect the correct position of the needle. Nerves are demonstrated as an composition of hyperechogenic (white) and hypoechogenic (black) areas. The surrounding hyperechogenic parts are epi- and perineurium, the dark hypoechogenic part is the neural tissue. The composition of peripheral nerves are always similar, but the quantities of each part, of surrounding perineurium and nerval structures, differ. Further the imaging of nerves is significantly influenced by the angle of beam to the nerve and the surrounding anatomic structures. Only experience and correct interpretation make the ultrasound a valid method in clinical practice. Correct interpretation has to be learned by standardized education. Three examples of peripheral nerve blocks are described. The detection of nerves and the visualization of the correct spread of local anesthetics to the nerves are the main principles of effective ultrasound-guided regional anesthesia, whereas closest proximity of the needle to the target nerve is not necessary. The described examples of ultrasound guidance for nerval block illustrates the specific procedures with reduced probability of nerval irritation, high success and low rate of
Efficient Distribution of Triggered Synchronous Block Diagrams
2011-10-21
called a trigger. At a given synchronous step, if the trigger is true , the block fires normally; otherwise, the block stutters , that is, keeps its...outputs have the same value as in the previous step, but they are still transmitted to downstream blocks. In this paper we present an implementation...optimizations that apply to general Triggered SBDs, we also present further optimizations for the case of Timed SBDs. 1.1 Motivating Examples Fig. 1
Advanced heart block in acute rheumatic fever.
Hubail, Zakariya; Ebrahim, Ishaq M
2016-04-01
First degree heart block is considered a minor criterion for the diagnosis of this condition. The cases presented here demonstrate that higher degrees of heart block do occur in rheumatic fever. Children presenting with acquired heart block should be worked-up for rheumatic fever. Likewise, it is imperative to serially follow the electrocardiogram in patients already diagnosed with acute rheumatic fever, as the conduction abnormalities can change during the course of the disease.
Advanced heart block in acute rheumatic fever
2015-01-01
First degree heart block is considered a minor criterion for the diagnosis of this condition. The cases presented here demonstrate that higher degrees of heart block do occur in rheumatic fever. Children presenting with acquired heart block should be worked-up for rheumatic fever. Likewise, it is imperative to serially follow the electrocardiogram in patients already diagnosed with acute rheumatic fever, as the conduction abnormalities can change during the course of the disease.
A New Relationship between Block Designs
Alexander Shramchenko
2016-01-01
Full Text Available We propose a procedure of constructing new block designs starting from a given one by looking at the intersections of its blocks with various sets and grouping those sets according to the structure of the intersections. We introduce a symmetric relationship of friendship between block designs built on a set V and consider families of block designs where all designs are friends of each other, the so-called friendly families. We show that a friendly family admits a partial ordering. Furthermore, we exhibit a map from the power set of V, partially ordered by inclusion, to a friendly family of a particular type which preserves the partial order.
Recent developments in paediatric neuraxial blocks
Vrushali Chandrashekhar Ponde
2012-01-01
Full Text Available Paediatric anaesthesia and paediatric regional anaesthesia are intertwined. Almost all surgeries unless contradicted could be and should be supplemented with a regional block. The main objective of this review is to elaborate on the recent advances of the central neuraxial blocks, such as application of ultrasound guidance and electrical stimulation in the pursuit of safety and an objective end point. This review also takes account of the traditional technique and understand the benefits as well the risk of each as compared with the recent technique. The recent trends in choosing the most appropriate peripheral block for a given surgery thereby sparing the central neuroaxis is considered. A penile block for circumcision or a sciatic block for unilateral foot surgery, rather than caudal epidural would have a better risk benefit equation. Readers will find a special mention on the recent thoughts on continuous epidural analgesia in paediatrics, especially its rise and fall, yet its unique importance. Lastly, the issue of block placements under sedation or general anaesthesia with its implication in this special population is dealt with. We conducted searches in MEDLINE (PubMed and assessed the relevance of the abstracts of citations identified from literature searches. The search was carried out in English, for last 10 years, with the following key words: Recent advances in paediatric regional anaesthesia; ultrasound guidance for central neuraxial blocks in children; role of electrical stimulation in neuraxial blocks in children; complications in neuraxial block. Full-text articles of potentially relevant abstracts were retrieved for further review.
Using Interference to Block RFID Tags
Krigslund, Rasmus; Popovski, Petar; Pedersen, Gert Frølund
We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag.......We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag....
Høskuldsson, Agnar; Svinning, K.
2006-01-01
Here is presented a unified approach to modelling multi-block regression data. The starting point is a partition of the data X into L data blocks, X = (X-1, X-2,...X-L), and the data Y into M data-blocks, Y = (Y-1, Y-2,...,Y-M). The methods of linear regression, X -> Y, are extended to the case...... these methods can be extended to a network of data blocks. Examples of the optimisation procedures in a network are shown. The examples chosen are the ones that are useful to work within industrial production environments. The methods are illustrated by simulated data and data from cement production....
Using Interference to Block RFID Tags
Krigslund, Rasmus; Popovski, Petar; Pedersen, Gert Frølund
We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag.......We propose a novel method to block RFID tags from responding, using intentional interference. We focus on the experimental evaluation, where we impose interference on the download and uplink, respectively. The results are positive, where modulated CCI shows most effective to block a tag....
PACS photometer calibration block analysis
Moór, A; Kiss, Cs; Balog, Z; Billot, N; Marton, G
2013-01-01
The absolute stability of the PACS bolometer response over the entire mission lifetime without applying any corrections is about 0.5% (standard deviation) or about 8% peak-to-peak. This fantastic stability allows us to calibrate all scientific measurements by a fixed and time-independent response file, without using any information from the PACS internal calibration sources. However, the analysis of calibration block observations revealed clear correlations of the internal source signals with the evaporator temperature and a signal drift during the first half hour after the cooler recycling. These effects are small, but can be seen in repeated measurements of standard stars. From our analysis we established corrections for both effects which push the stability of the PACS bolometer response to about 0.2% (stdev) or 2% in the blue, 3% in the green and 5% in the red channel (peak-to-peak). After both corrections we still see a correlation of the signals with PACS FPU temperatures, possibly caused by parasitic h...
Capturing Reality at Centre Block
Boulanger, C.; Ouimet, C.; Yeomans, N.
2017-08-01
The Centre Block of Canada's Parliament buildings, National Historic Site of Canada is set to undergo a major rehabilitation project that will take approximately 10 years to complete. In preparation for this work, Heritage Conservation Services (HCS) of Public Services and Procurement Canada has been completing heritage documentation of the entire site which includes laser scanning of all interior rooms and accessible confined spaces such as attics and other similar areas. Other documentation completed includes detailed photogrammetric documentation of rooms and areas of high heritage value. Some of these high heritage value spaces present certain challenges such as accessibility due to the height and the size of the spaces. Another challenge is the poor lighting conditions, requiring the use of flash or strobe lighting to either compliment or completely eliminate the available ambient lighting. All the spaces captured at this higher level of detail were also captured with laser scanning. This allowed the team to validate the information and conduct a quality review of the photogrammetric data. As a result of this exercise, the team realized that in most, if not all cases, the photogrammetric data was more detailed and at a higher quality then the terrestrial laser scanning data. The purpose and motivation of this paper is to present these findings, as well provide the advantages and disadvantages of the two methods and data sets.
CAPTURING REALITY AT CENTRE BLOCK
C. Boulanger
2017-08-01
Full Text Available The Centre Block of Canada’s Parliament buildings, National Historic Site of Canada is set to undergo a major rehabilitation project that will take approximately 10 years to complete. In preparation for this work, Heritage Conservation Services (HCS of Public Services and Procurement Canada has been completing heritage documentation of the entire site which includes laser scanning of all interior rooms and accessible confined spaces such as attics and other similar areas. Other documentation completed includes detailed photogrammetric documentation of rooms and areas of high heritage value. Some of these high heritage value spaces present certain challenges such as accessibility due to the height and the size of the spaces. Another challenge is the poor lighting conditions, requiring the use of flash or strobe lighting to either compliment or completely eliminate the available ambient lighting. All the spaces captured at this higher level of detail were also captured with laser scanning. This allowed the team to validate the information and conduct a quality review of the photogrammetric data. As a result of this exercise, the team realized that in most, if not all cases, the photogrammetric data was more detailed and at a higher quality then the terrestrial laser scanning data. The purpose and motivation of this paper is to present these findings, as well provide the advantages and disadvantages of the two methods and data sets.
Ruqaya M. Elsayed
2017-01-01
Conclusion: We concluded that ultrasound guided transversus abdominis plane block and thoracic paravertebral block were safe and effective anesthetic technique for upper abdominal surgery with longer and potent postoperative analgesia in thoracic paravertebral block than transversus abdominis block.
Block co-polypeptide and hydrogels made thereof
Wolf, de F.A.; Werten, M.W.T.; Moers, A.P.H.A.; Wolbert, E.J.H.; Eggink, G.
2009-01-01
Disclosed is a block co-polypeptide comprising at least two blocks T and at least one block S, with blocks T and S alternating, wherein each T independently denotes a Trimerizing Block being a polypeptide block capable of forming a thermoreversible collagen-like triple helix structure, and
Ionization of amphiphilic acidic block copolymers.
Colombani, Olivier; Lejeune, Elise; Charbonneau, Céline; Chassenieux, Christophe; Nicolai, Taco
2012-06-28
The ionization behavior of an amphiphilic diblock copolymer poly(n-butyl acrylate(50%)-stat-acrylic acid(50%))(100)-block-poly(acrylic acid)(100) (P(nBA(50%)-stat-AA(50%))(100)-b-PAA(100), DH50) and of its equivalent triblock copolymer P(nBA(50%)-stat-AA(50%))(100)-b-PAA(200)-b-P(nBA(50%)-stat-AA(50%))(100) (TH50) were studied by potentiometric titration either in pure water or in 0.5 M NaCl. These polymers consist of a hydrophilic acidic block (PAA) connected to a hydrophobic block, P(nBA(50%)-stat-AA(50%))(100), whose hydrophobic character has been mitigated by copolymerization with hydrophilic units. We show that all AA units, even those in the hydrophobic block could be ionized. However, the AA units within the hydrophobic block were less acidic than those in the hydrophilic block, resulting in the preferential ionization of the latter block. The preferential ionization of PAA over that of P(nBA(50%)-stat-AA(50%))(100) was stronger at higher ionic strength. Remarkably, the covalent bonds between the PAA and P(nBA(50%)-stat-AA(50%))(100) blocks in the diblock or the triblock did not affect the ionization of each block, although the self-association of the block copolymers into spherical aggregates modified the environment of the PAA blocks compared to when PAA was molecularly dispersed.
Erosion patterns on dissolving blocks
Courrech du Pont, Sylvain; Cohen, Caroline; Derr, Julien; Berhanu, Michael
2016-04-01
Patterns in nature are shaped under water flows and wind action, and the understanding of their morphodynamics goes through the identification of the physical mechanisms at play. When a dissoluble body is exposed to a water flow, typical patterns with scallop-like shapes may appear [1,2]. These shapes are observed on the walls of underground rivers or icebergs. We experimentally study the erosion of dissolving bodies made of salt, caramel or ice into water solutions without external flow. The dissolving mixture, which is created at the solid/liquid interface, undergoes a buoyancy-driven instability comparable to a Rayleigh-Bénard instability so that the dissolving front destabilizes into filaments. This mechanism yields to spatial variations of solute concentration and to differential dissolution of the dissolving block. We first observe longitudinal stripes with a well defined wavelength, which evolve towards chevrons and scallops that interact and move again the dissolving current. Thanks to a careful analysis of the competing physical mechanisms, we propose scaling laws, which account for the characteristic lengths and times of the early regime in experiments. The long-term evolution of patterns is understood qualitatively. A close related mechanism has been proposed to explain structures observed on the basal boundary of ice cover on brakish lakes [3] and we suggest that our experiments are analogous and explain the scallop-like patterns on iceberg walls. [1] P. Meakin and B. Jamtveit, Geological pattern formation by growth and dissolution in aqueous systems, Proc. R. Soc. A 466, 659-694 (2010). [2] P.N. Blumberg and R.L. Curl, Experimental and theoretical studies of dissolution roughness, J. Fluid Mech. 65, 735-751 (1974). [3] L. Solari and G. Parker, Morphodynamic modelling of the basal boundary of ice cover on brakish lakes, J.G.R. 118, 1432-1442 (2013).
Block-based image hashing with restricted blocking strategy for rotational robustness
Xiang, Shijun; Yang, Jianquan
2012-12-01
Image hashing is a potential solution for image content authentication (a desired image hashing algorithm should be robust to common image processing operations and various geometric distortions). In the literature, researchers pay more attention to block-based image hashing algorithms due to their robustness to common image processing operations (such as lossy compression, low-pass filtering, and additive noise). However, the block-based hashing strategies are sensitive to rotation processing operations. This indicates that the robustness of the block-based hashing methods against rotation operations is an important issue. Towards this direction, in this article we propose a restricted blocking strategy by investigating effect of two rotation operations on an image and its blocks in both theoretical and experimental ways. Furthermore, we apply the proposed blocking strategy for the recently reported non-negative matrix factorization (NMF) hashing. Experimental results have demonstrated the validity of the block-based hashing algorithms with restricted blocking strategy for rotation operations.
New routes to the synthesis of amylose-block-polystyrene rod-coil block copolymers
Loos, Katja; Müller, Axel H.E.
2002-01-01
Hybrid block copolymers amylose-block-polystyrene were synthesized by covalent attachment of maltoheptaose derivatives to end-functionalized polystyrene and subsequent enzymatic grafting from polymerization. The maltoheptaose derivatives were attached by reductive amination or hydrosilation to amino
Earthquake Resistant Submarine Drydock Block System Design
1988-05-01
acceleration time history. It Is observed that the block on block surfaces for this system had been painted. According to Rabinowicz (1987) [13J, a...Maryland, 1982, p. 272. 166 13. Rabinowicz , Ernest, Lecture, "Tribology", M.I.T., Course 2.800, Fall 1987. 14. Telephone conversation between Tingley
Micellization and Characterization of Block Copolymer Detergents
Hvidt, Søren
Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are used widely in industry as emulsifiers, anti-foaming agents, and in delayed drug release. EPE copolymers form micelles with a core of P blocks and different micellar shapes depen...
Haplotype block structure is conserved across mammals
Guryev, Victor; Smits, Bart M G; van de Belt, Jose; Verheul, Mark; Hubner, Norbert; Cuppen, Edwin
2006-01-01
Genetic variation in genomes is organized in haplotype blocks, and species-specific block structure is defined by differential contribution of population history effects in combination with mutation and recombination events. Haplotype maps characterize the common patterns of linkage disequilibrium i
Micellization and Characterization of Block Copolymer Detergents
Hvidt, Søren
Triblock copolymers of the type EPE, where E and P denote ethylene oxide and propylene oxide blocks, respectively, are used widely in industry as emulsifiers, anti-foaming agents, and in delayed drug release. EPE copolymers form micelles with a core of P blocks and different micellar shapes...
Content Analysis of Block Play Literature.
Conrad, Annabel
This study examined research on children's block play, using content analysis to review 75 documents that focused on such play. Each document was coded by type (empirical study or nonempirical article) and by 15 topics and 76 subtopics grouped into 4 broad categories: (1) environment/ecology; (2) block play and the school curriculum; (3) block…
CONJUGATED BLOCK-COPOLYMERS FOR ELECTROLUMINESCENT DIODES
Hilberer, A; Gill, R.E; Herrema, J.K; Malliaras, G.G; Wildeman, J.; Hadziioannou, G
1995-01-01
In this article we review results obtained in our laboratory on the design and study of new light-emitting polymers. We are interested in the synthesis and characterisation of block copolymers with regularly alternating conjugated and non conjugated sequences. The blocks giving rise to luminescence
Block Gas Sol Unit in Haderslev
Vejen, Niels Kristian
2000-01-01
Investigation of a SDHW system based on a Block Gas Sol Unit from Baxi A/S installed by a consumer i Haderslev, Denmark.......Investigation of a SDHW system based on a Block Gas Sol Unit from Baxi A/S installed by a consumer i Haderslev, Denmark....
Light extraction block with curved surface
Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.
2016-03-22
Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.
CONJUGATED BLOCK-COPOLYMERS FOR ELECTROLUMINESCENT DIODES
Hilberer, A; Gill, R.E; Herrema, J.K; Malliaras, G.G; Wildeman, J.; Hadziioannou, G
1995-01-01
In this article we review results obtained in our laboratory on the design and study of new light-emitting polymers. We are interested in the synthesis and characterisation of block copolymers with regularly alternating conjugated and non conjugated sequences. The blocks giving rise to luminescence
The Block Grant Record: Lessons from Experience.
Hastings, Anne H.
1982-01-01
Evaluates the performance of federal block grants in health, law enforcement, peoplepower training, community development, and Social Security programs, to help forecast the effects of such grants in education. Finds that block grants did not improve local control, accountability, citizen participation, efficiency, targeting of funds, or program…
C++ application development with Code::Blocks
Modak, Biplab Kumar
2013-01-01
This is a comprehensive tutorial with step-by-step instructions on how to develop applications with Code::Blocks.This book is for C++ developers who wish to use Code::Blocks to create applications with a consistent look and feel across multiple platforms. This book assumes that you are familiar with the basics of the C++ programming language.
PEO-related block copolymer surfactants
Mortensen, K.
2001-01-01
Non-ionic block copolymer systems based on hydrophilic poly(ethylene oxide) and more hydrophobic co-polymer blocks are used intensively in a variety of industrial and personal applications. A brief description on the applications is presented. The physical properties of more simple model systems ...
Luo, Dehai; Cha, Jing; Zhong, Linhao; Dai, Aiguo
2014-05-01
In this paper, a nonlinear multi-scale interaction (NMI) model is used to propose an eddy-blocking matching (EBM) mechanism to account for how synoptic eddies reinforce or suppress a blocking flow. It is shown that the spatial structure of the eddy vorticity forcing (EVF) arising from upstream synoptic eddies determines whether an incipient block can grow into a meandering blocking flow through its interaction with the transient synoptic eddies from the west. Under certain conditions, the EVF exhibits a low-frequency oscillation on timescales of 2-3 weeks. During the EVF phase with a negative-over- positive dipole structure, a blocking event can be resonantly excited through the transport of eddy energy into the incipient block by the EVF. As the EVF changes into an opposite phase, the blocking decays. The NMI model produces life cycles of blocking events that resemble observations. Moreover, it is shown that the eddy north-south straining is a response of the eddies to a dipole- or Ω-type block. In our model, as in observations, two synoptic anticyclones (cyclones) can attract and merge with one another as the blocking intensifies, but only when the feedback of the blocking on the eddies is included. Thus, we attribute the eddy straining and associated vortex interaction to the feedback of the intensified blocking on synoptic eddies. The results illustrate the concomitant nature of the eddy deformation, whose role as a PV source for the blocking flow becomes important only during the mature stage of a block. Our EBM mechanism suggests that an incipient block flow is amplified (or suppressed) under certain conditions by the EVF coming from the upstream of the blocking region.
Howell, Stephen M; Unger, M W Todd; Colson, James D; Serafini, Mario
2010-11-01
Ultrasound-guided regional anesthetic techniques have shown some advantages over conventional paresthesia and neurostimulation techniques. We report the case of a neurostimulation-guided continuous interscalene block that would have ended in complication were it not for experience with ultrasound-guided regional anesthesia. Familiarity with ultrasound-guided block techniques permitted assessment of a neck hematoma during interscalene block and ultimately allowed successful peripheral nerve block.
Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers
Ruggeri, Giacomo; Passaglia, Elisa; Giorgi, Ivan; Picchioni, Francesco; Aglietto, Mauro
2001-01-01
Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing sulfonated units were prepared by blending styrene-block-butadiene-block-styrene (SBS), with both sulfonated PS and sulfonated SEBS in a Brabender mixer. Such a procedure was performed as an alter...
Syncope and Idiopathic (Paroxysmal) AV Block.
Brignole, Michele; Deharo, Jean-Claude; Guieu, Regis
2015-08-01
Syncope due to idiopathic AV block is characterized by: 1) ECG documentation (usually by means of prolonged ECG monitoring) of paroxysmal complete AV block with one or multiple consecutive pauses, without P-P cycle lengthening or PR interval prolongation, not triggered by atrial or ventricular premature beats nor by rate variations; 2) long history of recurrent syncope without prodromes; 3) absence of cardiac and ECG abnormalities; 4) absence of progression to persistent forms of AV block; 5) efficacy of cardiac pacing therapy. The patients affected by idiopathic AV block have low baseline adenosine plasma level values and show an increased susceptibility to exogenous adenosine. The APL value of the patients with idiopathic AV block is much lower than patients affected by vasovagal syncope who have high adenosine values. Copyright © 2015 Elsevier Inc. All rights reserved.
The undesirable effects of neuromuscular blocking drugs
Claudius, C; Garvey, L H; Viby-Mogensen, J
2009-01-01
Neuromuscular blocking drugs are designed to bind to the nicotinic receptor at the neuromuscular junction. However, they also interact with other acetylcholine receptors in the body. Binding to these receptors causes adverse effects that vary with the specificity for the cholinergic receptor...... in question. Moreover, all neuromuscular blocking drugs may cause hypersensitivity reactions. Often the symptoms are mild and self-limiting but massive histamine release can cause systematic reactions with circulatory and respiratory symptoms and signs. At the end of anaesthesia, no residual effect...... of a neuromuscular blocking drug should be present. However, the huge variability in response to neuromuscular blocking drugs makes it impossible to predict which patient will suffer postoperative residual curarization. This article discusses the undesirable effects of the currently available neuromuscular blocking...
STUDY ON POLYSULFONE-POLYESTER BLOCK COPOLYMERS
DING Youjun; QI Daquan
1988-01-01
Synthesis and characterization of a series of Polysulfone (PSF)-Polyester (PEs) block copolymers were studied.The degree of randomness (B) of these block copolymers was calculated from the intensities of their proton signals in 1H NMR spectra and lies in the region of 0 ＜ B ＜ 1. It was shown that the degree of randomness (B) and the average sequence length (L) in block copolymers were relatively dependent on the reaction conditions, various feed ratios and structure of diols.The phenomenon was observed, when the PSF-PEs block copolymers dissolved in different solvents they had different viscosities and molecular conformations.The PSF-PEs block copolymers had better solvent resistance than homo-polysulfone.
Fermion RG blocking transformations and IR structure
Cheng, X
2011-01-01
We explore fermion RG block-spinning transformations on the lattice with the aim of studying the IR structure of gauge theories and, in particular, the existence of IR fixed points for varying fermion content. In the case of light fermions the main concern and difficulty is ensuring locality of any adopted blocking scheme. We discuss the problem of constructing a local blocked fermion action in the background of arbitrary gauge fields. We then discuss the carrying out of accompanying gauge field blocking. In the presence of the blocked fermions implementation of MCRG is not straightforward. By adopting judicious approximations we arrive at an easily implementable approximate RG recursion scheme that allows quick, inexpensive estimates of the location of conformal windows for various groups and fermion representations. We apply this scheme to locate the conformal windows in the case of SU(2) and SU(3) gauge groups. Some of the reasons for the apparent efficacy of this and similar decimation schemes are discuss...
Sympathetic blocks for visceral cancer pain management
Mercadante, Sebastiano; Klepstad, Pal; Kurita, Geana Paula
2015-01-01
The neurolytic blocks of sympathetic pathways, including celiac plexus block (CPB) and superior hypogastric plexus block (SHPB) , have been used for years. The aim of this review was to assess the evidence to support the performance of sympathetic blocks in cancer patients with abdominal visceral...... pain. Only comparison studies were included. All data from the eligible trials were analyzed using the GRADE system. Twenty-seven controlled studies were considered. CPB, regardless of the technique used, improved analgesia and/or decrease opioid consumption, and decreased opioid-induced adverse...... effects in comparison with a conventional analgesic treatment. In one study patients treated with superior hypogastric plexus block (SHPB) had a decrease in pain intensity and a less morphine consumption, while no statistical differences in adverse effects were found. The quality of these studies...
A note on "Block H-matrices and spectrum of block matrices"
LIU Jian-zhou; HUANG Ze-jun
2008-01-01
In this paper, we make further discussions and improvements on the results presented in the previously published work "Block H-matrices and spectrum of block matrices". Furthermore, a new bound for eigenvalues of block matrices is given with examples to show advantages of the new result.
Block Copolymers: Synthesis and Applications in Nanotechnology
Lou, Qin
This study is focused on the synthesis and study of (block) copolymers using reversible deactivation radical polymerizations (RDRPs), including atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) polymerization. In particular, two primary areas of study are undertaken: (1) a proof-of-concept application of lithographic block copolymers, and (2) the mechanistic study of the deposition of titania into block copolymer templates for the production of well-ordered titania nanostructures. Block copolymers have the ability to undergo microphase separation, with an average size of each microphase ranging from tens to hundreds of nanometers. As such, block copolymers have been widely considered for nanotechnological applications over the past two decades. The development of materials for various nanotechnologies has become an increasingly studied area as improvements in many applications, such as those found in the semiconductor and photovoltaic industries are constantly being sought. Significant growth in developments of new synthetic methods ( i.e. RDRPs) has allowed the production of block copolymers with molecular (and sometimes atomic) definition. In turn, this has greatly expanded the use of block copolymers in nanotechnology. Herein, we describe the synthesis of statistical and block copolymers of 193 nm photolithography methacrylate and acrylate resist monomers with norbornyl and adamantyl moieties using RAFT polymerization.. For these resist (block) copolymers, the phase separation behaviors were examined by atomic force microscopy (AFM). End groups were removed from the polymers to avoid complications during the photolithography since RAFT end groups absorb visible light. Poly(glycidyl methacrylate-block-polystyrene) (PGMA-b-PS) was synthesize by ATRP and demonstrated that this block copolymer acts as both a lithographic UV (365 nm) photoresist and a self-assembly material. The PGMA segments can undergo cationic
Development of Alkali Activated Geopolymer Masonry Blocks
Venugopal, K.; Radhakrishna; Sasalatti, Vinod
2016-09-01
Cement masonry units are not considered as sustainable since their production involves consumption of fuel, cement and natural resources and therefore it is essential to find alternatives. This paper reports on making of geopolymer solid & hollow blocks and masonry prisms using non conventional materials like fly ash, ground granulated blast furnace slag (GGBFS) and manufactured sand and curing at ambient temperature. They were tested for water absorption, initial rate of water absorption, dry density, dimensionality, compressive, flexural and bond-strength which were tested for bond strength with and without lateral confinement, modulus of elasticity, alternative drying & wetting and masonry efficiency. The properties of geopolymer blocks were found superior to traditional masonry blocks and the masonry efficiency was found to increase with decrease in thickness of cement mortar joints. There was marginal difference in strength between rendered and unrendered geopolymer masonry blocks. The percentage weight gain after 7 cycles was less than 6% and the percentage reduction in strength of geopolymer solid blocks and hollow blocks were 26% and 28% respectively. Since the properties of geopolymer blocks are comparatively better than the traditional masonry they can be strongly recommended for structural masonry.
DYNAMIC BEHAVIOR OF TYRE TREAD BLOCK
K. Sridharan
2012-01-01
Full Text Available The Tyre tread pattern is the arrangement of blocks, grooves and voids, sipes and channels designed into the tread to enhance its grip on the road. Tread is the uppermost part of any tyre which contact into the road and it has its own performance towards mileage, traction, low noise and heat built up properties. It would be meaningful to conduct an extended analysis on the tyre tread blocks for its performance in static and dynamic condition to predict its behavior and wear of tread block in on-road condition. The Finite Element software Abaqus is used for the present analysis of the tread block and its behavior was studied on two different contact surfaces. The tread block is modeled in six different shapes and analyzed for is performance. The deformation stress strain characteristic of different blocks is studied which will be useful in deciding the contact behavior, friction and road grip. The regular shape/geometry has common behavior and the mixed type geometry shows a distinguished variation in the analysis. The dynamic stiffness and deformed shape was analyzed in this study and it has its own effect in tyre design. The tread block dynamics study by geometric shape would be vital in tread pattern optimization to enhance the traction, better hydroplaning and rolling resistance under all operating conditions.
Circular block matching based video stabilization
Xu, Lidong; Fu, Fangwen; Lin, Xinggang
2005-07-01
Video sequences captured by handheld digital camera need to be stabilized to eliminate the tiresome effects caused by camera"s undesirable shake or jiggle. The key issue of video stabilization is to estimate the global motion parameters between two successive frames. In this paper, a novel circular block matching algorithm is proposed to estimate the global motion parameters. This algorithm can deal with not only translational motion but even large rotational motion. For an appointed circular block in current frame, a four-dimensional rotation invariant feature vector is firstly extracted from it and used to judge if it is an effective block. Then the rotation invariant features based circular block matching process is performed to find the best matching blocks in reference frame for those effective blocks. With the matching results of any two effective blocks, a two-dimensional motion model is constructed to produce one group of frame motion parameters. A statistical method is proposed to calculate the estimated global motion parameters with all groups of global motion parameters. Finally, using the estimated motion parameters as the initial values, an iteration algorithm is introduced to obtain the refined global motion parameters. The experimental results show that the proposed algorithm is excellent in stabilizing frames with even burst global translational and rotational motions.
Gaussian curvature analysis allows for automatic block placement in multi-block hexahedral meshing.
Ramme, Austin J; Shivanna, Kiran H; Magnotta, Vincent A; Grosland, Nicole M
2011-10-01
Musculoskeletal finite element analysis (FEA) has been essential to research in orthopaedic biomechanics. The generation of a volumetric mesh is often the most challenging step in a FEA. Hexahedral meshing tools that are based on a multi-block approach rely on the manual placement of building blocks for their mesh generation scheme. We hypothesise that Gaussian curvature analysis could be used to automatically develop a building block structure for multi-block hexahedral mesh generation. The Automated Building Block Algorithm incorporates principles from differential geometry, combinatorics, statistical analysis and computer science to automatically generate a building block structure to represent a given surface without prior information. We have applied this algorithm to 29 bones of varying geometries and successfully generated a usable mesh in all cases. This work represents a significant advancement in automating the definition of building blocks.
Lidocaine block of cardiac sodium channels
Bean, BP; Cohen, CJ; Tsien, RW
1983-01-01
Lidocaine block of cardiac sodium channels was studied in voltage-clamped rabbit purkinje fibers at drug concentrations ranging from 1 mM down to effective antiarrhythmic doses (5-20 μM). Dose-response curves indicated that lidocaine blocks the channel by binding one-to-one, with a voltage-dependent K(d). The half-blocking concentration varied from more than 300 μM, at a negative holding potential where inactivation was completely removed, to approximately 10 μM, at a depolarized holding pote...
Measurement of soil moisture using gypsum blocks
Friis Dela, B.
the building. Consequently, measuring the moisture of the surrounding soil is of great importance for detecting the source of moisture in a building. Up till now, information has been needed to carry out individual calibrations for the different types of gypsum blocks available on the market and to account......For the past 50 years, gypsum blocks have been used to determine soil moisture content. This report describes a method for calibrating gypsum blocks for soil moisture measurements. Moisture conditions inside a building are strongly influenced by the moisture conditions in the soil surrounding...
Measurement of soil moisture using gypsum blocks
Friis Dela, B.
For the past 50 years, gypsum blocks have been used to determine soil moisture content. This report describes a method for calibrating gypsum blocks for soil moisture measurements. Moisture conditions inside a building are strongly influenced by the moisture conditions in the soil surrounding...... the building. Consequently, measuring the moisture of the surrounding soil is of great importance for detecting the source of moisture in a building. Up till now, information has been needed to carry out individual calibrations for the different types of gypsum blocks available on the market and to account...
Theory of circuit block switch-off
S. Henzler
2004-01-01
Full Text Available Switching-off unused circuit blocks is a promising approach to supress static leakage currents in ultra deep sub-micron CMOS digital systems. Basic performance parameters of Circuit Block Switch-Off (CBSO schemes are defined and their dependence on basic circuit parameters is estimated. Therefore the design trade-off between strong leakage suppression in idle mode and adequate dynamic performance in active mode can be supported by simple analytic investigations. Additionally, a guideline for the estimation of the minimum time for which a block deactivation is useful is derived.
Readiness for surgery after axillary block
Koscielniak-Nielsen, Z J; Stens-Pedersen, H L; Lippert, F K
1997-01-01
We have assessed prospectively the time to readiness for surgery following axillary block (sum of block performance and latency times) in 80 patients. The brachial plexus was identified using a nerve stimulator, and anaesthetized with 45 mL of mepivacaine 1% with adrenaline 5 micrograms mL-1....... In group 1 (single injection) the whole volume of mepivacaine was injected after locating only one of the plexus nerves. In group 2 (multiple injections) at least three plexus nerves were located, and the volume of mepivacaine was divided between them. Sensory block was assessed by a blinded observer every...
Evaluative Conditioning is Insensitive to Blocking
Tom Beckers
2009-01-01
Full Text Available Evaluative conditioning has been claimed to have a number of functional characteristics that set it apart from other forms of associative learning in humans, such as insensitivity to extinction and contingency, independence of contingency awareness, and insensitivity to modulation. Despite its potential theoretical importance, until now few data are available concerning the susceptibility of evaluative conditioning to cue competition effects such as blocking. In the present study, we assessed the susceptibility of acquired preferences and evaluations to blocking in a candy game. Results suggest that evaluative conditioning is not susceptible to blocking. We discuss this observation in the light of theoretical accounts of evaluative conditioning and associative learning in humans.
Comparative Analysis of Sandcrete Hollow Blocks and Laterite Interlocking Blocks as Walling Elements
Akeem Ayinde Raheem
2012-04-01
Full Text Available This study considered the production and testing of sandcrete hollow blocks and laterite interlocking blocks with a view to comparing their physical characteristics and production cost. Some units of sandcrete hollow blocks and laterite interlocking blocks were made using machine vibrated sandcrete block mould and hydraulic interlocking block making machine respectively. The blocks were tested to determine their density and compressive strength. The results obtained from the tests were compared with the specifications of Nigerian Building and Road Research Institute (2006, Nigerian Building Code (2006, and Nigerian Industrial Standards (2000. The results indicated that the compressive strength of 225mm and 150mm sandcrete hollow blocks varies from 1.59 N/mm2 to 4.25 N/mm2 and 1.48N/mm2 to 3.35N/mm2 respectively, as the curing age increases from 7 to 28 days. For laterite interlocking blocks, the strength varies from 1.70N/mm2 at 7 days to 5.03N/mm2 at 28 days. All the blocks produced satisfied the minimum requirements in terms of compressive strength, by all available codes. The cost per square metre of 225mm and 150mm sandcrete hollow blocks are ₦2,808:00 and ₦2,340:00 respectively, while that of laterite interlocking blocks is ₦2,121:20.It was concluded that laterite interlocking blocks have better strength and are cheaper than sandcrete hollow blocks.
EnviroAtlas - Fresno, CA - Block Groups
U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Fresno, CA EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...
EnviroAtlas - Portland, OR - Block Groups
U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Portland, OR EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...
Functionalization of Block Copolymer Vesicle Surfaces
Wolfgang Meier
2011-01-01
Full Text Available In dilute aqueous solutions certain amphiphilic block copolymers self-assemble into vesicles that enclose a small pool of water with a membrane. Such polymersomes have promising applications ranging from targeted drug-delivery devices, to biosensors, and nanoreactors. Interactions between block copolymer membranes and their surroundings are important factors that determine their potential biomedical applications. Such interactions are influenced predominantly by the membrane surface. We review methods to functionalize block copolymer vesicle surfaces by chemical means with ligands such as antibodies, adhesion moieties, enzymes, carbohydrates and fluorophores. Furthermore, surface-functionalization can be achieved by self-assembly of polymers that carry ligands at their chain ends or in their hydrophilic blocks. While this review focuses on the strategies to functionalize vesicle surfaces, the applications realized by, and envisioned for, such functional polymersomes are also highlighted.
Formation of Anisotropic Block Copolymer Gels
Liaw, Chya Yan; Shull, Kenneth; Henderson, Kevin; Joester, Derk
2011-03-01
Anisotropic, fibrillar gels are important in a variety of processes. Biomineralization is one example, where the mineralization process often occurs within a matrix of collagen or chitin fibers that trap the mineral precursors and direct the mineralization process. We wish to replicate this type of behavior within block copolymer gels. Particularly, we are interested in employing gels composed of cylindrical micelles, which are anisotropic and closely mimic biological fibers. Micelle geometry is controlled in our system by manipulating the ratio of molecular weights of the two blocks and by controlling the detailed thermal processing history of the copolymer solutions. Small-Angle X-ray Scattering and Dynamic Light Scattering are used to determine the temperature dependence of the gel formation process. Initial experiments are based on a thermally-reversible alcohol-soluble system, that can be subsequently converted to a water soluble system by hydrolysis of a poly(t-butyl methacrylate) block to a poly (methacrylic acid) block. MRSEC.
EnviroAtlas - Milwaukee, WI - Block Groups
U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Milwaukee, WI EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...
A Smart Thermal Block Diagram Tool
Tsuyuki, Glenn; Miyake, Robert; Dodge, Kyle
2008-01-01
The presentation describes a Smart Thermal Block Diagram Tool. It is used by JPL's Team X in studying missions during the Pre-Phase A. It helps generate cost and mass estimates using proprietary data bases.
Seizure complicating interscalene brachail plexus block | Idehen ...
Seizure complicating interscalene brachail plexus block. ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL · RESOURCES ... We describe a case of seizure occurring immediately after completion of ...
Extrinsic germanium Blocked Impurity Bank (BIB) detectors
Krabach, Timothy N.; Huffman, James E.; Watson, Dan M.
1989-01-01
Ge:Ga blocked-impurity-band (BIB) detectors with long wavelength thresholds greater than 190 microns and peak quantum efficiencies of 4 percent, at an operating temperature of 1.8 K, have been fabricated. These proof of concept devices consist of a high purity germanium blocking layer epitaxially grown on a Ga-doped Ge substrate. This demonstration of BIB behavior in germanium enables the development of far infrared detector arrays similar to the current silicon-based devices. Present efforts are focussed on improving the chemical vapor deposition process used to create the blocking layer and on the lithographic processing required to produce monolithic detector arrays in germanium. Approaches to test the impurity levels in both the blocking and active layers are considered.
EnviroAtlas - Phoenix, AZ - Block Groups
U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Phoenix, AZ EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...
EnviroAtlas - Cleveland, OH - Block Groups
U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Cleveland, OH EnviroAtlas community. The block groups are from the US Census Bureau and are included/excluded...
EnviroAtlas - Paterson, NJ - Block Groups
U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Paterson, NJ EnviroAtlas area. The block groups are from the US Census Bureau and are included/excluded based on...
EnviroAtlas - Memphis, TN - Block Groups
U.S. Environmental Protection Agency — This EnviroAtlas dataset is the base layer for the Memphis, TN EnviroAtlas community. The block groups are from the US Census Bureau and are included/excluded based...
Evidence of peripheral nerve blocks for cancer-related pain
Klepstad, P; Kurita, G P; Mercadante, S
2015-01-01
retrieved was 155. No controlled studies were identified. Sixteen papers presented a total of 79 cases. The blocks applied were paravertebral blocks (10 cases), blocks in the head region (2 cases), plexus blocks (13 cases), intercostal blocks (43 cases) and others (11 cases). In general, most cases reported...
Algorithms for Finding the Inverses of Factor Block Circulant Matrices
无
2006-01-01
In this paper, algorithms for finding the inverse of a factor block circulant matrix,a factor block retrocirculant matrix and partitioned matrix with factor block circulant blocks over the complex field are presented respectively. In addition, two algorithms for the inverse of a factor block circulant matrix over the quaternion division algebra are proposed.
Differential cryptanalysis of round-reduced PRINTcipher: Computing roots of permutations
Abdelraheem, Mohamed Ahmed; Leander, Gregor; Zenner, Erik
2011-01-01
At CHES 2010, the new block cipher PRINTcipher was presented. In addition to using an xor round key as is common practice for round-based block ciphers, PRINTcipher also uses key-dependent permutations. While this seems to make differential cryptanalysis difficult due to the unknown bit permutati...
An update on the side channel cryptanalysis of MACs based on cryptographic hash functions
Gauravaram, Praveen; Okeya, Katsuyuki
2007-01-01
into consideration. Next, we propose new hybrid NMAC/HMAC schemes for security against side channel attacks assuming that their underlying block cipher is ideal. We then show that M-NMAC, MDx-MAC and a variant of the envelope MAC scheme based on DM with an ideal block cipher are secure against DPA attacks....
On the distribution of linear biases: Three instructive examples
Abdelraheem, Mohamed Ahmed; Beelen, Peter; Leander, Gregor;
2012-01-01
Despite the fact that we evidently have very good block ciphers at hand today, some fundamental questions on their security are still unsolved. One such fundamental problem is to precisely assess the security of a given block cipher with respect to linear cryptanalysis. In by far most of the case...
Adaptive cosine transform image coding with variable block size and constant block distortion
Daut, David G.; Wu, Jia-Chyi
1996-02-01
An adaptive discrete cosine transform (DCT) image coding system is implemented with the same average distortion designated for each variable size image block. The variable block size segmentation is performed using a quadtree data structure by dividing the perceptually more important regions of an image into smaller size blocks compared to the size of blocks containing lesser amounts of spatial activity. Due to the nonstationarity of real-world images, each image block is described by a space-varying nonstationary Gauss-Markov random field. The space-varying autoregressive parameters are estimated using an on-line modified least- squares estimator. For each assumed space-varying nonstationary image block, a constant average distortion is assigned and the code rate for each image block is allowed to vary in order to meet the fixed distortion criterion. Simulation results show that reconstructed images coded at low average distortion, based on an assumed space-varying nonstationary image model, using variable size blocks and with variable bit rate per block possess high-quality subjective (visual) and objective (measured) quality at low average bit rates. Performance gains are achieved due to the distortion being distributed more uniformly among the blocks as compared with fixed-rate, stationary image transform coding schemes.
Building-block selectivity of polyketide synthases.
Liou, Grace F; Khosla, Chaitan
2003-04-01
For the past decade, polyketide synthases have presented an exciting paradigm for the controlled manipulation of complex natural product structure. These multifunctional enzymes catalyze the biosynthesis of polyketide natural products by stepwise condensation and modification of metabolically derived building blocks. In particular, regioselective modification of polyketide structure is possible by alterations in either intracellular acyl-CoA pools or, more commonly, by manipulation of acyl transferases that act as the primary gatekeepers for building blocks.
Permutations with Ascending and Descending Blocks
Steinhardt, Jacob
2009-01-01
We investigate permutations in terms of their cycle structure and descent set. To do this, we generalize the classical bijection of Gessel and Reutenauer to deal with permutations that have some ascending and some descending blocks. We then provide the first bijective proofs of some known results. We also solve some problems posed in [3] by Eriksen, Freij, and Wastlund, who study derangements that descend in blocks of prescribed lengths.
deepBlockAlign: a tool for aligning RNA-seq profiles of read block patterns
Ekstrøm, Claus T.; Stadler, Peter F.; Hoffmann, Steve; Gorodkin, Jan
2012-01-01
Motivation: High-throughput sequencing methods allow whole transcriptomes to be sequenced fast and cost-effectively. Short RNA sequencing provides not only quantitative expression data but also an opportunity to identify novel coding and non-coding RNAs. Many long transcripts undergo post-transcriptional processing that generates short RNA sequence fragments. Mapped back to a reference genome, they form distinctive patterns that convey information on both the structure of the parent transcript and the modalities of its processing. The miR-miR* pattern from microRNA precursors is the best-known, but by no means singular, example. Results: deepBlockAlign introduces a two-step approach to align RNA-seq read patterns with the aim of quickly identifying RNAs that share similar processing footprints. Overlapping mapped reads are first merged to blocks and then closely spaced blocks are combined to block groups, each representing a locus of expression. In order to compare block groups, the constituent blocks are first compared using a modified sequence alignment algorithm to determine similarity scores for pairs of blocks. In the second stage, block patterns are compared by means of a modified Sankoff algorithm that takes both block similarities and similarities of pattern of distances within the block groups into account. Hierarchical clustering of block groups clearly separates most miRNA and tRNA, and also identifies about a dozen tRNAs clustering together with miRNA. Most of these putative Dicer-processed tRNAs, including eight cases reported to generate products with miRNA-like features in literature, exhibit read blocks distinguished by precise start position of reads. Availability: The program deepBlockAlign is available as source code from http://rth.dk/resources/dba/. Contact: gorodkin@rth.dk; studla@bioinf.uni-leipzig.de Supplementary information: Supplementary data are available at Bioinformatics online. PMID:22053076
Adaptive overlapped sub-blocks contrast enhancement
Chen, Anqiu; Yuan, Fei; Liu, Jing; Liu, Siqi; Li, An; Zheng, Zhenrong
2016-09-01
In this paper, an overlapped sub-block gray-level average method for contrast enhancement is presented. The digital image correction of uneven illumination under microscope transmittance is a problem in image processing, also sometimes the image in the dark place need to correct the uneven problem. A new correction method was proposed based on the mask method and sub-blocks gray-level average method because Traditional mask method and background fitting method are restricted due to application scenarios, and the corrected image brightness is low by using background fitting method, so it has some limitations of the application. In this paper, we introduce a new method called AOSCE for image contrast enhancement. The image is divided into many sub-blocks which are overlapped, calculate the average gray-level of the whole image as M and the calculate the average gray-level of each one as mi, next for each block it can get d = mi - m, each block minus d to get a new image, and then get the minimum gray-level of each block into a matrix DD to get the background, and use bilinearity to get the same scale of the image. over fitting the image in matlab in order to get smoother image, then minus the background to get the contrast enhancement image.
Dietary cholesterol modulates pathogen blocking by Wolbachia.
Eric P Caragata
Full Text Available The bacterial endosymbiont Wolbachia pipientis protects its hosts from a range of pathogens by limiting their ability to form infections inside the insect. This "pathogen blocking" could be explained by innate immune priming by the symbiont, competition for host-derived resources between pathogens and Wolbachia, or the direct modification of the cell or cellular environment by Wolbachia. Recent comparative work in Drosophila and the mosquito Aedes aegypti has shown that an immune response is not required for pathogen blocking, implying that there must be an additional component to the mechanism. Here we have examined the involvement of cholesterol in pathogen blocking using a system of dietary manipulation in Drosophila melanogaster in combination with challenge by Drosophila C virus (DCV, a common fly pathogen. We observed that flies reared on cholesterol-enriched diets infected with the Wolbachia strains wMelPop and wMelCS exhibited reduced pathogen blocking, with viral-induced mortality occurring 2-5 days earlier than flies reared on Standard diet. This shift toward greater virulence in the presence of cholesterol also corresponded to higher viral copy numbers in the host. Interestingly, an increase in dietary cholesterol did not have an effect on Wolbachia density except in one case, but this did not directly affect the strength of pathogen blocking. Our results indicate that host cholesterol levels are involved with the ability of Wolbachia-infected flies to resist DCV infections, suggesting that cholesterol contributes to the underlying mechanism of pathogen blocking.
Capacitor blocks for linear transformer driver stages.
Kovalchuk, B M; Kharlov, A V; Kumpyak, E V; Smorudov, G V; Zherlitsyn, A A
2014-01-01
In the Linear Transformer Driver (LTD) technology, the low inductance energy storage components and switches are directly incorporated into the individual cavities (named stages) to generate a fast output voltage pulse, which is added along a vacuum coaxial line like in an inductive voltage adder. LTD stages with air insulation were recently developed, where air is used both as insulation in a primary side of the stages and as working gas in the LTD spark gap switches. A custom designed unit, referred to as a capacitor block, was developed for use as a main structural element of the transformer stages. The capacitor block incorporates two capacitors GA 35426 (40 nF, 100 kV) and multichannel multigap gas switch. Several modifications of the capacitor blocks were developed and tested on the life time and self breakdown probability. Blocks were tested both as separate units and in an assembly of capacitive module, consisting of five capacitor blocks. This paper presents detailed design of capacitor blocks, description of operation regimes, numerical simulation of electric field in the switches, and test results.
Tunable Morphologies from Charged Block Copolymers
Goswami, Monojoy [ORNL; Sumpter, Bobby G [ORNL; Mays, Jimmy [ORNL; Messman, Jamie M [ORNL
2010-01-01
The bulk morphologies formed by a new class of charged block copolymers, 75 vol % fluorinated polyisoprene (FPI) 25 vol% sulfonated polystyrene (PSS) with 50% sulfonation, are characterized, and the fundamental underlying forces that promote the self-assembly processes are elucidated. The results show how the bulk morphologies are substantially different from their uncharged diblock counterparts (PS-PI) and also how morphology can be tuned with volume fraction of the charged block and the casting solvent. A physical understanding based on the underlying strong electrostatic interactions between the charged block and counterions is obtained using Monte Carlo (MC) and Molecular Dynamics (MD) simulations. The 75/25 FPI-PSS shows hexagonal morphologies with the minority blocks (PSS) forming the continuous phase due to charge percolation and the FPI blocks arranged in hexagonal cylinders. Some long-range order can be sustained even if lipophobicity is increased (addition of water), albeit with lower dimensional structures. However, thermal annealing provides sufficient energy to disrupt the percolated charges and promotes aggregation of ionic sites which leads to a disordered system. Diverse and atypical morphologies are readily accessible by simply changing the number distribution of the charges on PSS block.
Helical Ordering in Chiral Block Copolymers
Zhao, Wei; Hong, Sung Woo; Chen, Dian; Grason, Gregory; Russell, Thomas
2012-02-01
Introducing molecular chirality into the segments of block copolymers can influence the nature of the resultant morphology. Such an effect was found for poly(styrene-b-L-lactide) (PS-b-PLLA) diblock copolymers where hexagonally packed PLLA helical microdomains (H* phase) form in a PS matrix. However, molecular ordering of PLLA within the helical microdomains and the transfer of chirality from the segmental level to the mesoscale is still not well understood. We developed a field theoretic model to describe the interactions between segments of chiral blocks, which have the tendency to form a ``cholesteric'' texture. Based on the model, we calculated the bulk morphologies of chiral AB diblock copolymers using self-consistent field theory (SCFT). Experiments show that the H* phase only forms when microphase separation between PS and PLLA block happens first and crystallization of PLLA block is suppressed or happens within confined microdomain. Hence, crystalline ordering is not necessary for H* phase formation. The SCFT offers the chance to explore the range of thermodynamic stability of helical structures in the phase diagram of chiral block copolymer melts, by tuning parameters not only like the block segregation strength and composition, but also new parameters such as the ratio between preferred helical pitch to the radius of gyration and the Frank elastic constant for inter-segment distortions.
Block copolymer membranes for aqueous solution applications
Nunes, Suzana Pereira
2016-03-22
Block copolymers are known for their intricate morphology. We review the state of the art of block copolymer membranes and discuss perspectives in this field. The main focus is on pore morphology tuning with a short introduction on non-porous membranes. The two main strategies for pore formation in block copolymer membranes are (i) film casting and selective block sacrifice and (ii) self-assembly and non-solvent induced phase separation (SNIPS). Different fundamental aspects involved in the manufacture of block copolymer membranes are considered, including factors affecting the equilibrium morphology in solid films, self-assembly of copolymer in solutions and macrophase separation by solvent-non-solvent exchange. Different mechanisms are proposed for different depths of the SNIPS membrane. Block copolymer membranes can be prepared with much narrower pore size distribution than homopolymer membranes. Open questions and indications of what we consider the next development steps are finally discussed. They include the synthesis and application of new copolymers and specific functionalization, adding characteristics to respond to stimuli and chemical environment, polymerization-induced phase separation, and the manufacture of organic-inorganic hybrids.
Kroeze, E; ten Brinke, G.; Hadziioannou, G
1995-01-01
A technique is described for the synthesis of segmented poly(butadiene-block-styrene) block copolymers and segmented poly(butadiene-block-(styrene-co-acrylonitrile)) block copolymers through polybutadiene-based thermal iniferters. Dihydroxy- and dicarboxy-terminated polybutadienes were transformed i
The Early Paleozoic paleogeography of the North China block and the other major blocks of China
无
2000-01-01
With the summarization of the Early Paleozoic paleomagnetic data recently obtained from the three major blocks of China, the Early Paleozoic (I.e. Cambrian and Ordovician) paleogeographic positions of the North China, South China and Tarim blocks were discussed in detail. The North China, South China and Tarim blocks were inferred to be located adjacent to East Gondwana in low latitudes of the Southern Hemisphere during the Early Cambrian. During the Early-Middle Ordovician, the South China and Tarim blocks were also located in low latitudes of the Southern Hemisphere with some affinities of the Gondwanaland, whereas the North China block may have episodically separated from the Gondwanaland, and might be sited close to the North America and Siberia. The reestablished paleogeographic configurations are in agreement with the studies on the biogeography, paleoclimate and sedimental facies of the North China and South China blocks.
Adductor canal block versus femoral nerve block for analgesia after total knee arthroplasty
Jaeger, Pia; Zaric, Dusanka; Fomsgaard, Jonna Storm
2013-01-01
Femoral nerve block (FNB), a commonly used postoperative pain treatment after total knee arthroplasty (TKA), reduces quadriceps muscle strength essential for mobilization. In contrast, adductor canal block (ACB) is predominately a sensory nerve block. We hypothesized that ACB preserves quadriceps...... muscle strength as compared with FNB (primary end point) in patients after TKA. Secondary end points were effects on morphine consumption, pain, adductor muscle strength, morphine-related complications, and mobilization ability....
Zheng Yue; Deng Xu Wang; Jing Quan Liu; Jie Zhang; Sheng Yu Feng
2012-01-01
A new A-B-A type of block copolymers,polyacrylonitrile-block-polydimethylsiloxane-block-polyacrylonitrile (PAN-b-PDMS-b-PAN),which comprises two polymer blocks of different polarities and compatibilities,were synthesized for the first time via reversible addition-fragmentation chain transfer polymerization.Reaction kinetics was investigated.PAN-b-PDMS-b-PAN films were prepared by spin-coating on glass chips.Significant order on the film surface morphologies was observed.(C) 2012 Jie Zhang.Published by Elsevier B.V.on behalf of Chinese Chemical Society.All rights reserved.
A potential vorticity perspective on atmospheric blocking?
Croci Maspoli, M.; Schwierz, C.
2003-04-01
A persistent large-scale anomaly of the west to east flow in the midlatitudes with a weakening and meridional splitting of the jet can be specified as atmospheric blocking. Lifetimes last from several days up to weeks so that blocking can therefore significantly determine monthly circulation index values. The vertical range affected by this phenomenon covers the entire troposphere as mirrored in increased surface pressure as well as an elevated tropopause and is also felt in the lower-stratosphere. Here we seek to shed more light on the physical mechanisms related to blocking by adopting the PV (potential vorticity) perspective with a focus on tropopause-level dynamics. Processes such as Rossby-wave breaking and diabatic heating can modify the conservative behaviour of the PV and are therefore important features for the formation and maintenance of atmospheric blocking. This motivates the definition of a novel blocking index based upon the three-dimensional structure of the phenomenon. A vertically integrated measure (PV within the 500 - 150 hPa layer, VIPV) is calculated, underlining the quasi-barotropic nature of blocked atmospheric state. Benefits of the new index include: representation of the two-dimensional structure of the phenomenon, its lifecycle and geographical distribution. The investigation is conducted over the period 1979 to 2001 using ECMWF reanalysis data. Characteristics of the VIPV field are presented. The new VIPV index is compared to a standard blocking index (e.g. Tibaldi and Molteni (1989)) on a case study basis and also with respect to seasonal variability. Relations to climate modes/indices (NAO, AO) are also discussed.
[Effectiveness of sympathetic block using various technics].
Weissenberg, W
1987-07-01
Blocking of sympathetic conduction aims at permanent or temporary elimination of those pain pathways conducted by the sympathetic nervous system. In order to provide an objective evaluation of sufficient blocking effect, earlier inquiries referred to parameters such as: (1) observation of clinical signs such as Horner's syndrome, Guttman's sign, anhidrosis, extended venous filling; (2) difference in skin temperature of at least 1.5 degrees C between blocked and unblocked side; (3) increase in amplitude of the pulse wave; and (4) depression of the psychogalvanic reflex (PGR) on the blocked side (Fig. 1). In clinical practice, these control parameters are effective because they are time-saving, technically simple, and highly evidential. Further parameters for evaluating sympathetic blockade are examination of hydrosis by means of color indicators such as bromocresol and ninhydrin, oscillometry, and plethysmography. The effectiveness of sympathetic blockade after stellate ganglion and sympathetic trunk blocks has been verified by various authors. In a clinical study, 16 patients were divided into four groups in order to test the effectiveness of sympathetic blockade after spinal anesthesia with 3 ml 0.75% bupivacaine (group I) and 4 ml 0.75% bupivacaine (group II) and after peridural anesthesia with 15 ml 0.75% bupivacaine (group III) and 20 ml 0.75% bupivacaine (group IV) by means of temperature difference, response of pulse wave amplitude and PGR between blocked lower and unblocked upper extremity, and sensory levels of block. The patients were classified as ASA I and II; their ages varied from 20 to 63 years.(ABSTRACT TRUNCATED AT 250 WORDS)
Decomposition of Data Mining Algorithms into Unified Functional Blocks
Ivan Kholod
2016-01-01
Full Text Available The present paper describes the method of creating data mining algorithms from unified functional blocks. This method splits algorithms into independently functioning blocks. These blocks must have unified interfaces and implement pure functions. The method allows us to create new data mining algorithms from existing blocks and improves the existing algorithms by optimizing single blocks or the whole structure of the algorithms. This becomes possible due to a number of important properties inherent in pure functions and hence functional blocks.
Peripheral nerve blocks for hip fractures.
Guay, Joanne; Parker, Martyn J; Griffiths, Richard; Kopp, Sandra
2017-05-11
Various nerve blocks with local anaesthetic agents have been used to reduce pain after hip fracture and subsequent surgery. This review was published originally in 1999 and was updated in 2001, 2002, 2009 and 2017. This review focuses on the use of peripheral nerves blocks as preoperative analgesia, as postoperative analgesia or as a supplement to general anaesthesia for hip fracture surgery. We undertook the update to look for new studies and to update the methods to reflect Cochrane standards. For the updated review, we searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 8), MEDLINE (Ovid SP, 1966 to August week 1 2016), Embase (Ovid SP, 1988 to 2016 August week 1) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (EBSCO, 1982 to August week 1 2016), as well as trial registers and reference lists of relevant articles. We included randomized controlled trials (RCTs) involving use of nerve blocks as part of the care provided for adults aged 16 years and older with hip fracture. Two review authors independently assessed new trials for inclusion, determined trial quality using the Cochrane tool and extracted data. When appropriate, we pooled results of outcome measures. We rated the quality of evidence according to the GRADE Working Group approach. We included 31 trials (1760 participants; 897 randomized to peripheral nerve blocks and 863 to no regional blockade). Results of eight trials with 373 participants show that peripheral nerve blocks reduced pain on movement within 30 minutes of block placement (standardized mean difference (SMD) -1.41, 95% confidence interval (CI) -2.14 to -0.67; equivalent to -3.4 on a scale from 0 to 10; I(2) = 90%; high quality of evidence). Effect size was proportionate to the concentration of local anaesthetic used (P mobilization after surgery (mean difference -11.25 hours, 95% CI -14.34 to -8.15 hours; I(2) = 52%; moderate quality of evidence). One trial
Wafaa Mohamed Alsadek
2015-04-01
Conclusion: TAP block and caudal block under ultrasound guidance proved to be safe with no recorded complications either intra or postoperatively. Patient and parent satisfaction was markedly observed in case of TAP block.
MPEG recompression detection based on block artifacts
Luo, Weiqi; Wu, Min; Huang, Jiwu
2008-02-01
With sophisticated video editing technologies, it is becoming increasingly easy to tamper digital video without leaving visual clues. One of the common tampering operations on video is to remove some frames and then re-encode the resulting video. In this paper, we propose a new method for detecting this type of tampering by exploring the temporal patterns of the block artifacts in video sequences. We show that MPEG compression introduces different block artifacts into various types of frames and that the strength of the block artifacts as a function over time has a regular pattern for a given group of pictures (GOP) structure. When some frames are removed from an MPEG video file and the file is then recompressed, the block artifacts introduced by the previous compression would remain and affect the average of block artifact strength of the recompressed one in such a way that depends on the number of deleted frames and the type of GOP used previously. We propose a feature curve to reveal the compression history of an MPEG video file with a given GOP structure, and use it as evidence to detect tampering. Experimental results evaluated on common video benchmark clips demonstrate the effectiveness of the proposed method.
Chain exchange in block copolymer micelles
Lu, Jie; Bates, Frank; Lodge, Timothy
2014-03-01
Block copolymer micelles are aggregates formed by self-assembly of amphiphilic copolymers dispersed in a selective solvent, driven by unfavorable interactions between the solvent and the core-forming block. Due to the relatively long chains being subject to additional thermodynamic and dynamic constraints (e.g., entanglements, crystallinity, vitrification), block copolymer micelles exhibit significantly slower equilibration kinetics than small molecule surfactants. As a result, details of the mechanism(s) of equilibration in block copolymer micelles remain unclear. This present works focuses on the chain exchange kinetics of poly(styrene-b-ethylenepropylene) block copolymers in squalane (C30H62) using time-resolved small angle neutron scattering (TR-SANS). A mixture of h-squalane and d-squalane is chosen so that it contrast matches a mixed 50/50 h/d polystyrene micelle core. When the temperature is appropriate and isotopically labeled chains undergo mixing, the mean core contrast with respect to the solvent decreases, and the scattering intensity is therefore reduced. This strategy allows direct probing of chain exchange rate from the time dependent scattering intensity I(q, t).
Haplotype block structure is conserved across mammals.
Victor Guryev
2006-07-01
Full Text Available Genetic variation in genomes is organized in haplotype blocks, and species-specific block structure is defined by differential contribution of population history effects in combination with mutation and recombination events. Haplotype maps characterize the common patterns of linkage disequilibrium in populations and have important applications in the design and interpretation of genetic experiments. Although evolutionary processes are known to drive the selection of individual polymorphisms, their effect on haplotype block structure dynamics has not been shown. Here, we present a high-resolution haplotype map for a 5-megabase genomic region in the rat and compare it with the orthologous human and mouse segments. Although the size and fine structure of haplotype blocks are species dependent, there is a significant interspecies overlap in structure and a tendency for blocks to encompass complete genes. Extending these findings to the complete human genome using haplotype map phase I data reveals that linkage disequilibrium values are significantly higher for equally spaced positions in genic regions, including promoters, as compared to intergenic regions, indicating that a selective mechanism exists to maintain combinations of alleles within potentially interacting coding and regulatory regions. Although this characteristic may complicate the identification of causal polymorphisms underlying phenotypic traits, conservation of haplotype structure may be employed for the identification and characterization of functionally important genomic regions.
Natural convection through enclosed disconnected solid blocks
Lao, Fernando Cesar De; Junqueira, Silvio L.M.; Franco, Admilson T. [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)]. E-mails: fernandodelai@gmail.com; silvio@utfpr.edu.br; admilson@utfpr.edu.br; Lage, Jose L. [Southern Methodist University (SMU), Dallas, TX (United States)]. E-mail: JLL@smu.edu
2008-07-01
In this study, the natural convection inside a fluid filled, enclosure containing several solid obstructions and being heated from the side is modeled and numerically simulated. The solid obstructions are equally spaced, conducting, and disconnected square blocks. The mathematical model is based on the balance equations of mass, momentum and energy, which are then solved numerically via the finite-volume method with the SIMPLEST algorithm and the HYBRID scheme. The effects of varying the solid-fluid thermal conductivity ratio (K), the fluid volume-fraction or porosity ({phi}), the number of solid blocks (N) and the heating strength (represented by the Rayleigh number, Ra) of the enclosure on the Nusselt number based on the surface-averaged heat transfer coefficient along the heated wall of the enclosure are studied. The results indicate a competing effect caused by the proximity of the solid blocks to the heated and cooled walls, vis-a-vis hindering the boundary layer growth, hence reducing the heat transfer effectiveness, and at the same time enhancing the heat transfer when the blocks' thermal conductivity is larger than that of the fluid. An analytical estimate of the minimum number of blocks beyond which the convection hindrance becomes predominant is presented and validated by the numerical results. (author)
Mineral resources estimation based on block modeling
Bargawa, Waterman Sulistyana; Amri, Nur Ali
2016-02-01
The estimation in this paper uses three kinds of block models of nearest neighbor polygon, inverse distance squared and ordinary kriging. The techniques are weighting scheme which is based on the principle that block content is a linear combination of the grade data or the sample around the block being estimated. The case study in Pongkor area, here is gold-silver resource modeling that allegedly shaped of quartz vein as a hydrothermal process of epithermal type. Resources modeling includes of data entry, statistical and variography analysis of topography and geological model, the block model construction, estimation parameter, presentation model and tabulation of mineral resources. Skewed distribution, here isolated by robust semivariogram. The mineral resources classification generated in this model based on an analysis of the kriging standard deviation and number of samples which are used in the estimation of each block. Research results are used to evaluate the performance of OK and IDS estimator. Based on the visual and statistical analysis, concluded that the model of OK gives the estimation closer to the data used for modeling.
Data Privacy Framework on Multi Check-out Timestamp Order for Secured Transaction in Mobile Network
Byambasuren Byamba
2011-01-01
Full Text Available Data transaction over distri uted network has gained much attention in the database communities since the last decade, especially in terms of security support. There are several data privacy models for mobile computing such as Data Encryption Standard, Skipjack, RC5 and so on. Most of the cipher algorithms are designed for huge data size of encryption and decryption processes. Therefore, a suitable secure cipher algorithm is needed if the encryption and decryption is merely for small amount of data such as in the mobile database environment. In this paper, we discuss on the five well-known symmetric key cryptographic ciphers and propose a framework for the security model on top of Multi Check-out Timestamp Order (MCTO data transaction model.
Partial transmission block production for real efficient method of block and MLC
Choi, Ji Min; Park, Ju Young; Ju, Sang Kyu; Park, Jong Ho [Dept. of Radiation Oncology, Samsung Medical Center, Sunkyunkwan University, Seoul (Korea, Republic of)
2004-09-15
The Vaginal, the urethra, the vulva and anal cancer avoid the many dose to femur head and the additional treatment is necessary in inguinal LN. The partial transmission block to use inguinal LN addition there is to a method which it treats and produce partial transmission block a method and the MLC which to it analyzes. The Inguinal the LN treatment patient partial transmission it used block and the MLC in the object and with solid water phantom with the patient it reappeared the same depth. In order to analyze the error of the junction the EDR2 (Extended dose range, the Kodak and the U.S) it used the Film and it got film scanner it got the beam profile. The partial transmission block and the MLC bias characteristic, accuracy and stability of production for, it shared at hour and comparison it analyzed. The partial the transmission block compares in the MLC and the block production is difficult and production hour also above 1 hours. The custom the block the place where it revises the error of the junction is a difficult problem. If use of the MLC the fabrication will be break and only the periodical calibration of the MLC it will do and it will be able to use easily. The Inguinal there is to LN treatment and partial transmission block and the MLC there is efficiency of each one but there is a place where the junction of block for partial transmission block the production hour is caught long and it fixes and a point where the control of the block is difficult. Like this problem it transfers with the MLC and if it treats, it means the effective treatment will be possible.
La Colla, Luca; Ben-David, Bruce; Merman, Rita
2017-01-01
Quadratus lumborum (QL) block was first described several years ago, but few articles have been published regarding this technique, for the most part case series involving abdominal surgery. We report 2 cases of prolonged, extensive block of thoracic and lumbar dermatomes after QL block in patients undergoing different hip surgery procedures for whom QL block was used in place of lumbar plexus block. Further prospective studies comparing these 2 techniques are necessary to better characterize the role of QL block in hip surgery.
Effects of 4X4 Block Scheduling
R. Brian Cobb
1999-02-01
Full Text Available The effects of a 4 X 4 block scheduling program in a middle school on a variety of student measures were investigated. These measures included standardized achievement tests in mathematics, reading, and writing, cumulative and semester grades in middle school and high school, attendance rates, and enrollment rates in advanced high school courses (in mathematics only. The block scheduling program had been in effect for four years allowing analyses of current middle and high school students who had experienced a minimum of one and one-half years of block scheduling while in middle school. The primary research design was a post-test only, matched pairs design. Students were matched on school characteristics, gender, ethnicity, grade level, and 5th grade standardized reading scores. Results were relatively consistent with the extant literature and generally positive.
Radial expansion for spinning conformal blocks
Costa, Miguel; Hansen, Tobias; Penedones, João; Trevisani, Emilio
2016-01-01
This paper develops a method to compute any bosonic conformal block as a series expansion in the optimal radial coordinate introduced by Hogervorst and Rychkov. The method reduces to the known result when the external operators are all the same scalar operator, but it allows to compute conformal blocks for external operators with spin. Moreover, we explain how to write closed form recursion relations for the coefficients of the expansions. We study three examples of four point functions in detail: one vector and three scalars; two vectors and two scalars; two spin 2 tensors and two scalars. Finally, for the case of two external vectors, we also provide a more efficient way to generate the series expansion using the analytic structure of the blocks as a function of the scaling dimension of the exchanged operator.
Concentration Dependent Structure of Block Copolymer Solutions
Choi, Soohyung; Bates, Frank S.; Lodge, Timothy P.
2015-03-01
Addition of solvent molecules into block copolymer can induce additional interactions between the solvent and both blocks, and therefore expands the range of accessible self-assembled morphologies. In particular, the distribution of solvent molecules plays a key role in determining the microstructure and its characteristic domain spacing. In this study, concentration dependent structures formed by poly(styrene-b-ethylene-alt-propylene) (PS-PEP) solution in squalane are investigated using small-angle X-ray scattering. This reveals that squalane is essentially completely segregated into the PEP domains. In addition, the conformation of the PS block changes from stretched to nearly fully relaxed (i.e., Gaussian conformation) as amounts of squalane increases. NRF
Additive-driven assembly of block copolymers
Lin, Ying; Daga, Vikram; Anderson, Eric; Watkins, James
2011-03-01
One challenge to the formation of well ordered hybrid materials is the incorporation of nanoscale additives including metal, semiconductor and dielectric nanoparticles at high loadings while maintaining strong segregation. Here we describe the molecular and functional design of small molecule and nanoparticle additives that enhance phase segregation in their block copolymer host and enable high additive loadings. Our approach includes the use of hydrogen bond interactions between the functional groups on the additive or particle that serve as hydrogen bond donors and one segment of the block copolymer containing hydrogen bond acceptors. Further, the additives show strong selectively towards the targeted domains, leading to enhancements in contrast between properties of the phases. In addition to structural changes, we explore how large changes in the thermal and mechanical properties occur upon incorporation of the additives. Generalization of this additive-induced ordering strategy to various block copolymers will be discussed.
Can neural blocks prevent phantom limb pain?
Borghi, Battista; D'Addabbo, Marco; Borghi, Raffaele
2014-07-01
Phantom limb syndrome (PLS) is a syndrome including stump pain, phantom limb pain and not-painful phantom sensations, which involves a large part of amputee patients and often has devastating effects on their quality of life. The efficacy of standard therapies is very poor. Nerve blocks have been investigated for the treatment and prevention of PLS. Epidural and peripheral blocks limited to the first three postamputation days can only reduce acute pain but cannot prevent the later development of PLS. Recent studies have shown that ambulatory prolonged peripheral nerve block (up to 30 days postamputation) may represent a new possible option to treat phantom pain and prevent the development of PLS and chronic pain.
Rapid ordering of block copolymer thin films
Majewski, Pawel W.; Yager, Kevin G.
2016-10-01
Block-copolymers self-assemble into diverse morphologies, where nanoscale order can be finely tuned via block architecture and processing conditions. However, the ultimate usage of these materials in real-world applications may be hampered by the extremely long thermal annealing times—hours or days—required to achieve good order. Here, we provide an overview of the fundamentals of block-copolymer self-assembly kinetics, and review the techniques that have been demonstrated to influence, and enhance, these ordering kinetics. We discuss the inherent tradeoffs between oven annealing, solvent annealing, microwave annealing, zone annealing, and other directed self-assembly methods; including an assessment of spatial and temporal characteristics. We also review both real-space and reciprocal-space analysis techniques for quantifying order in these systems.
Consensus recommendations for anaesthetic peripheral nerve block.
Santos Lasaosa, S; Cuadrado Pérez, M L; Guerrero Peral, A L; Huerta Villanueva, M; Porta-Etessam, J; Pozo-Rosich, P; Pareja, J A
2017-06-01
Anaesthetic block, alone or in combination with other treatments, represents a therapeutic resource for treating different types of headaches. However, there is significant heterogeneity in patterns of use among different professionals. This consensus document has been drafted after a thorough review and analysis of the existing literature and our own clinical experience. The aim of this document is to serve as guidelines for professionals applying anaesthetic blocks. Recommendations are based on the levels of evidence of published studies on migraine, trigeminal autonomic cephalalgias, cervicogenic headache, and pericranial neuralgias. We describe the main technical and formal considerations of the different procedures, the potential adverse reactions, and the recommended approach. Anaesthetic block in patients with headache should always be individualised and based on a thorough medical history, a complete neurological examination, and expert technical execution. Copyright © 2016 Sociedad Española de Neurología. Publicado por Elsevier España, S.L.U. All rights reserved.
Understanding dwarf galaxies as galactic building blocks
Tosi, M P
2003-01-01
This is a summary of a general discussion held during the third EuroConference on galaxy evolution. Various observational features of the stellar populations in present--day dwarf galaxies were presented to introduce the discussion on the possibility that these systems be the main building blocks of spiral and elliptical galaxies. Many people in the audience turned out to think that the inconsistencies among the observed properties of large and dwarf galaxies are too many to believe that the former are built up only by means of successive accretions of the latter. However, theorists of hierarchical galaxy formation suggested that present--day dwarfs are not representative of the galactic building blocks, which may be completely invisible nowadays. Some of them suggested that, contrary to what is usually assumed in hierarchical modelling, the actual building blocks were still fully gaseous systems when their major mergers occurred. If this is the case, then most of the inconsistencies can be overcome, and the ...
Production blocking and idea generation : Does blocking interfere with cognitive processes?
Nijstad, BA; Stroebe, W; Lodewijkx, HFM
2003-01-01
Production blocking (group members must take turns expressing their ideas) is an important cause of productivity loss in brainstorming groups. However, it is not yet clear why production blocking has this detrimental effect. We hypothesized that delays between the generation and articulation of idea
Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers
Ruggeri, Giacomo; Passaglia, Elisa; Giorgi, Ivan; Picchioni, Francesco; Aglietto, Mauro
2001-01-01
Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing
Blending of styrene-block-butadiene-block-styrene copolymer with sulfonated vinyl aromatic polymers
Ruggeri, Giacomo; Passaglia, Elisa; Giorgi, Ivan; Picchioni, Francesco; Aglietto, Mauro
2001-01-01
Different polymers containing sulfonic groups attached to the phenyl rings were prepared by sulfonation of polystyrene (PS) and styrene-block-(ethylene-co-1-butene)-block-styrene (SEBS). The sulfonation degree (SD) was varied between 1 and 20 mol% of the styrene units. Polyphase materials containing
无
2010-01-01
A series of controllable amphiphilic block copolymers composed of poly(ethylene oxide)(PEO) as the hydrophilic block and poly(ε-caprolactone)(PCL) as the hydrophobic block with the amino terminal group at the end of the PEO chain(PCL-b-PEO-NH2) were synthesized.Based on the further reaction of reactive amino groups,diblock copolymers with functional carboxyl groups(PCL-b-PEO-COOH) and functional compounds RGD(PCL-b-PEO-RGD) as well as the triblock copolymers with thermosensitive PNIPAAm blocks(PCL-b-PEO-b-PNIPAAM) were synthesized.The well-controlled structures of these copolymers with functional groups and blocks were characterized by gel permeation chromatography(GPC) and 1H NMR spectroscopy.These copolymers with functionalized hydrophilic blocks were fabricated into microspheres for the examination of biofunctions via cell culture experiments and in vitro drug release.The results indicated the significance of introducing functional groups(e.g.,NH2,COOH and RGD) into the end of the hydrophilic block of amphiphilic block copolymers for biomedical potentials in tissue engineering and controlled drug release.
Seligman, Amanda I.
2005-01-01
In the decades following World War II, cities across the United States saw an influx of African American families into otherwise homogeneously white areas. This racial transformation of urban neighborhoods led many whites to migrate to the suburbs, producing the phenomenon commonly known as white flight. In "Block by Block," Amanda I. Seligman…
31 CFR 547.204 - Expenses of maintaining blocked physical property; liquidation of blocked property.
2010-07-01
... physical property; liquidation of blocked property. 547.204 Section 547.204 Money and Finance: Treasury... TREASURY DEMOCRATIC REPUBLIC OF THE CONGO SANCTIONS REGULATIONS Prohibitions § 547.204 Expenses of..., all expenses incident to the maintenance of physical property blocked pursuant to § 547.201(a) shall...
Performance of Laterite-Cement Blocks as Walling Units in Relation to Sandcrete Blocks
James Isiwu AGUWA
2010-12-01
Full Text Available A study of the performance of laterite-cement blocks as walling materials in relation to those of sandcrete was conducted, for the purpose of establishing a cheaper building material in Minna, Niger state, Nigeria and surrounding towns, in the present ever increasing cost of building material. An A-2-6 laterite according to the AASHTO classification system was stabilized with 0-10% cement content by weight of the soil at a constant interval of 2% to produce 20 blocks of size 100mm × 100mm × 100mm for each mix. One hundred laterite-cement blocks were produced, cured under laboratory conditions and subjected to compressive strength test at 7, 14, 21, and 28-days of age, in five applications for each cement mix ratio. The average compressive strength was determined from five blocks crushed in each mix at every age of curing and the same procedure was repeated using sandcrete blocks. At a common cement content of 6%, the compressive strengths, densities, water absorption and the cost per square metre of wall for both types of blocks were determined. The study recommends the use of laterite-cement blocks as walling materials in Minna and environs because it has better engineering properties and more economical with a saving of 30% per square metre of wall when compared with the use of sandcrete blocks.
Lidocaine block of cardiac sodium channels.
Bean, B P; Cohen, C J; Tsien, R W
1983-05-01
Lidocaine block of cardiac sodium channels was studied in voltage-clamped rabbit purkinje fibers at drug concentrations ranging from 1 mM down to effective antiarrhythmic doses (5-20 muM). Dose-response curves indicated that lidocaine blocks the channel by binding one-to-one, with a voltage-dependent K(d). The half-blocking concentration varied from more than 300 muM, at a negative holding potential where inactivation was completely removed, to approximately 10 muM, at a depolarized holding potential where inactivation was nearly complete. Lidocaine block showed prominent use dependence with trains of depolarizing pulses from a negative holding potential. During the interval between pulses, repriming of I (Na) displayed two exponential components, a normally recovering component (tauless than 0.2 s), and a lidocaine-induced, slowly recovering fraction (tau approximately 1-2 s at pH 7.0). Raising the lidocaine concentration magnified the slowly recovering fraction without changing its time course; after a long depolarization, this fraction was one-half at approximately 10 muM lidocaine, just as expected if it corresponded to drug-bound, inactivated channels. At less than or equal to 20 muM lidocaine, the slowly recovering fraction grew exponentially to a steady level as the preceding depolarization was prolonged; the time course was the same for strong or weak depolarizations, that is, with or without significant activation of I(Na). This argues that use dependence at therapeutic levels reflects block of inactivated channels, rather than block of open channels. Overall, these results provide direct evidence for the "modulated-receptor hypothesis" of Hille (1977) and Hondeghem and Katzung (1977). Unlike tetrodotoxin, lidocaine shows similar interactions with Na channels of heart, nerve, and skeletal muscle.
Peripheral nerve blocks in pediatric anesthesia
Novaković Dejan
2009-01-01
Full Text Available Introduction Most children undergoing surgery can benefit from regional anesthetic techniques, either as the sole anesthetic regimen or, as usual in pediatric practice, in combination with general anesthesia. The use of peripheral nerve blocks (PNBs in pediatric anesthesia is an effective way to decrease the side-effects and complications associated with central blocks. In spite of their many advantages, including easy performance end efficacy, peripheral nerve blocks are still underused. Objective This article discusses a general approach to PNBs in children and provides data concerning the practice of this regional technique in different age groups. Methods Data from 1,650 procedures were prospectively collected during the period from March 1, 2007 to February 29, 2008. The type of PNB, if any, as well as the patient age were noted. Our patients were divided into four groups: 0-3 years, 4-7 years, 8-12 years and 13-18 years. Results During the investigated period, PNBs as a sole technique or in anesthetized children were performed in 7.45% of cases. Ilioingunal/iliohypogastric nerve block and penile block were the most common (70% of all PNBs distributed mainly among the children between 4-7 years of age (p<0.05. In older children, extremity PNBs predominate in regard to other types of blocks. PNBs are most frequently performed under general anesthesia (85%, so the perineural approach requires a safe technique to avoid nerve damage. Conclusion The observed differences in PNB usage seem to be related to patient age and correlate with common pathology and also with technical availability of PNB performance.
Block floating point for radar data
Christensen, Erik Lintz
1999-01-01
Integer, floating point, and block floating point (BFP) data formats are analyzed and compared in order to establish the mathematical tools for selection of an optimal format which fulfils the demands of high resolution radar (SAR) data to large dynamic range and adequate S/N. The analysis takes...... quantization noise and saturation distortion into account and concludes that it is preferred to use small blocks and a (new) modified BFP format applying fractional exponents. Data from the EMISAR radar system are applied to illustrate the merits of the different schemes....
Ophthalmic regional blocks: management, challenges, and solutions
Palte HD
2015-08-01
Full Text Available Howard D Palte Department of Anesthesiology, Perioperative Medicine and Pain Management, Miller School of Medicine, University of Miami, Miami, FL, USA Abstract: In the past decade ophthalmic anesthesia has witnessed a major transformation. The sun has set on the landscape of ophthalmic procedures performed under general anesthesia at in-hospital settings. In its place a new dawn has ushered in the panorama of eye surgeries conducted under regional and topical anesthesia at specialty eye care centers. The impact of the burgeoning geriatric population is that an increasing number of elderly patients will present for eye surgery. In order to accommodate increased patient volumes and simultaneously satisfy administrative initiatives directed at economic frugality, administrators will seek assistance from anesthesia providers in adopting measures that enhance operating room efficiency. The performance of eye blocks in a holding suite meets many of these objectives. Unfortunately, most practicing anesthesiologists resist performing ophthalmic regional blocks because they lack formal training. In future, anesthesiologists will need to block eyes and manage common medical conditions because economic pressures will eliminate routine preoperative testing. This review addresses a variety of topical issues in ophthalmic anesthesia with special emphasis on cannula and needle-based blocks and the new-generation antithrombotic agents. In a constantly evolving arena, the sub-Tenon’s block has gained popularity while the deep angulated intraconal (retrobulbar block has been largely superseded by the shallower extraconal (peribulbar approach. Improvements in surgical technique have also impacted anesthetic practice. For example, phacoemulsification techniques facilitate the conduct of cataract surgery under topical anesthesia, and suture-free vitrectomy ports may cause venous air embolism during air/fluid exchange. Hyaluronidase is a useful adjuvant because it
A solar air apartment block, Gothenburg, Sweden
Nordstrom, C.
1999-07-01
A double envelope solar air system was installed in a 1950s three-storey apartment block when it was renovated in 1986. The system saves 40% compared to identical conventionally renovated buildings, thanks to the following: The south-facing side of the roof has been converted to a 350 m{sup 2} solar air collector. An extra insulated facade with an integrated air-space of 900 m{sup 2} has been added to all surrounding walls. A DHW system including a 12 m{sup 3} storage tank has been added in order to provide solar heated water to four blocks (96 apartments) during the summer. (author)
Conformal blocks in the QCD Pomeron formalism
Navelet, H
1996-01-01
The conformal invariance properties of the QCD Pomeron in the transverse plane allow us to give an explicit analytical expression for the conformal eigenvectors in the mixed representation in terms of two conformal blocks, each block being the product of an holomorphic times an antiholomorphic function. This property is used to give an exact expression for various functions of interest, the Pomeron amplitude in both momentum and impact-parameter variables, the QCD dipole multiplicities and dipole-dipole cross-sections in the whole parameter space, and we recover the expression of the four-point gluon Green function given recently by Lipatov
Wilson loop invariants from WN conformal blocks
Oleg Alekseev
2015-12-01
Full Text Available Knot and link polynomials are topological invariants calculated from the expectation value of loop operators in topological field theories. In 3D Chern–Simons theory, these invariants can be found from crossing and braiding matrices of four-point conformal blocks of the boundary 2D CFT. We calculate crossing and braiding matrices for WN conformal blocks with one component in the fundamental representation and another component in a rectangular representation of SU(N, which can be used to obtain HOMFLY knot and link invariants for these cases. We also discuss how our approach can be generalized to invariants in higher-representations of WN algebra.
Superconvergence of tricubic block finite elements
2009-01-01
In this paper, we first introduce interpolation operator of projection type in three dimen- sions, from which we derive weak estimates for tricubic block finite elements. Then using the estimate for the W 2, 1-seminorm of the discrete derivative Green’s function and the weak estimates, we show that the tricubic block finite element solution uh and the tricubic interpolant of projection type Πh3u have superclose gradient in the pointwise sense of the L∞-norm. Finally, this supercloseness is applied to superconvergence analysis, and the global superconvergence of the finite element approximation is derived.
Quantization of the space of conformal blocks
Mukhin, E
1997-01-01
We consider the discrete Knizhnik-Zamolodchikov connection (qKZ) associated to $gl(N)$, defined in terms of rational R-matrices. We prove that under certain resonance conditions, the qKZ connection has a non-trivial invariant subbundle which we call the subbundle of quantized conformal blocks. The subbundle is given explicitly by algebraic equations in terms of the Yangian $Y(gl(N))$ action. The subbundle is a deformation of the subbundle of conformal blocks in CFT. The proof is based on an identity in the algebra with two generators $x,y$ and defining relation $xy=yx+yy$.
Heart block following propofol in a child.
Sochala, C; Deenen, D; Ville, A; Govaerts, M J
1999-01-01
We present the case of a nine-year-old boy afflicted with Ondine's curse, who developed complete atrioventricular heart block after a single bolus of propofol for induction of anaesthesia for strabismus surgery. Ondine's curse, the other name for congenital central hypoventilation syndrome, is characterized by a generalized disorder of autonomic function. Propofol has no effect on the normal atrioventricular conduction system in humans but it reduces sympathetic activity and can highly potentiate other vagal stimulation factors. Heart block has been documented after propofol bolus use in adults but, to our knowledge, not in children. It would appear that propofol is not a good choice for anaesthesia in congenital central hypoventilation syndrome.
Building indifferentiable compression functions from the PGV compression functions
Gauravaram, P.; Bagheri, Nasour; Knudsen, Lars Ramkilde
2016-01-01
Preneel, Govaerts and Vandewalle (PGV) analysed the security of single-block-length block cipher based compression functions assuming that the underlying block cipher has no weaknesses. They showed that 12 out of 64 possible compression functions are collision and (second) preimage resistant. Black...... cipher is ideal. We address the problem of building indifferentiable compression functions from the PGV compression functions. We consider a general form of 64 PGV compression functions and replace the linear feed-forward operation in this generic PGV compression function with an ideal block cipher...... independent of the one used in the generic PGV construction. This modified construction is called a generic modified PGV (MPGV). We analyse indifferentiability of the generic MPGV construction in the ideal cipher model and show that 12 out of 64 MPGV compression functions in this framework...
Heparin-containing block copolymers, Part I: Surface characterization
Vulić, I.; Pijpers, A.P.; Okano, T.; Kim, S.W.; Feijen, J.
1993-01-01
Newly synthesized heparin-containing block copolymers, consisting of a hydrophobic block of polystyrene (PS), a hydrophilic spacer-block of poly(ethylene oxide) (PEO) and covalently bound heparin (Hep) as bioactive block, were coated on aluminium, glass, polydimethylsiloxane (PDMS), PS or Biomer sub
30 CFR 250.511 - Traveling-block safety device.
2010-07-01
... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Traveling-block safety device. 250.511 Section... Traveling-block safety device. All units being used for well-completion operations that have both a traveling block and a crown block must be equipped with a safety device that is designed to prevent...
30 CFR 250.611 - Traveling-block safety device.
2010-07-01
... 30 Mineral Resources 2 2010-07-01 2010-07-01 false Traveling-block safety device. 250.611 Section... Traveling-block safety device. After May 31, 1989, all units being used for well-workover operations which have both a traveling block and a crown block shall be equipped with a safety device which is...
Heparin-containing block copolymers; Part I: Surface characterization
Vulić, I.; Pijpers, A.P.; Okano, T.; Kim, S.W.; Feijen, Jan
1993-01-01
Newly synthesized heparin-containing block copolymers, consisting of a hydrophobic block of polystyrene (PS), a hydrophilic spacer-block of poly(ethylene oxide) (PEO) and covalently bound heparin (Hep) as bioactive block, were coated on aluminium, glass, polydimethylsiloxane (PDMS), PS or Biomer
Nylon 46-polytetramethylene oxide segmented block copolymers
Gaymans, R.J.; Schwering, P.; Haan, de J.L.
1989-01-01
Block copolymers were synthesized from amine-terminated polytetramethylene oxide (PMTO) (Mw 800 and 1130) and polyamide 4,6 salt. First prepolymers were prepared at 200–210°C in the presence of a solvent (pyrrolidone). The prepolymers were postcondensed at 255°C (where possible in the solid state) t
BLOCK BASED NEWTON-LIKE BLENDING INTERPOLATION
Qian-jin Zhao; Jie-qing Tan
2006-01-01
Newton's polynomial interpolation may be the favourite linear interpolation in the sense that it is built up by means of the divided differences which can be calculated recursively and produce useful intermediate results. However Newton interpolation is in fact point based interpolation since a new interpolating polynomial with one more degree is obtained by adding a new support point into the current set of support points once at a time. In this paper we extend the point based interpolation to the block based interpolation. Inspired by the idea of the modern architectural design, we first divide the original set of support points into some subsets (blocks), then construct each block by using whatever interpolation means, linear or rational and finally assemble these blocks by Newton's method to shape the whole interpolation scheme. Clearly our method offers many flexible interpolation schemes for choices which include the classical Newton's polynomial interpolation as its special case. A bivariate analogy is also discussed and numerical examples are given to show the effectiveness of our method.
CLINICAL PHARMACOKINETICS OF NEUROMUSCULAR BLOCKING-DRUGS
AGOSTON, S; VANDENBROM, RHG; WIERDA, JMKH
1992-01-01
Neuromuscular blocking agents provide muscle relaxation for a great variety of surgical procedures with light planes of general anaesthesia. Besides having a significant impact in the development of anaesthesia and surgery, these agents continue to play an important role as pharmacological tools in
Defying Gravity Using Jenga[TM] Blocks
Tan, Yin-Soo; Yap, Kueh-Chin
2007-01-01
This paper describes how Jenga[TM] blocks can be used to demonstrate the physics of an overhanging tower that appears to defy gravity. We also propose ideas for how this demonstration can be adapted for the A-level physics curriculum. (Contains 8 figures and 1 table.)
Charge Transport in Conjugated Block Copolymers
Smith, Brandon; Le, Thinh; Lee, Youngmin; Gomez, Enrique
Interest in conjugated block copolymers for high performance organic photovoltaic applications has increased considerably in recent years. Polymer/fullerene mixtures for conventional bulk heterojunction devices, such as P3HT:PCBM, are severely limited in control over interfaces and domain length scales. In contrast, microphase separated block copolymers self-assemble to form lamellar morphologies with alternating electron donor and acceptor domains, thereby maximizing electronic coupling and local order at interfaces. Efficiencies as high as 3% have been reported in solar cells for one block copolymer, P3HT-PFTBT, but the details concerning charge transport within copolymers have not been explored. To fill this gap, we probed the transport characteristics with thin-film transistors. Excellent charge mobility values for electron transport have been observed on aluminum source and drain contacts in a bottom gate, bottom contact transistor configuration. Evidence of high mobility in ordered PFTBT phases has also been obtained following thermal annealing. The insights gleaned from our investigation serve as useful guideposts, revealing the significance of the interplay between charge mobility, interfacial order, and optimal domain size in organic block copolymer semiconductors.
Prenatal diagnosis of congenital complete heart block.
Costa, Patrícia; Carriço, Ana; Ramalho, Carla; Matias, Alexandra; Monterroso, José; Areias, José Carlos
2007-06-01
Congenital complete heart block (CHB) is a conduction defect with an incidence in the general population of 1/15,000 to 1/22,000 live births. It is frequently associated with structural heart defects or maternal autoimmune disease. We describe a case of CHB associated with maternal systemic lupus erythematosus and review our previous cases and experience of CHB.
Block Toeplitz operators with rational symbols (II)
Hwang, In Sung [Department of Mathematics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Woo Young [Department of Mathematics, Seoul National University, Seoul 151-742 (Korea, Republic of)], E-mail: ishwang@skku.edu, E-mail: wylee@math.snu.ac.kr
2008-09-26
In this paper we derive a formula for the rank of the self-commutator of hyponormal block Toeplitz operators T{sub {phi}} with matrix-valued rational symbols {phi} in L{sup {infinity}}(C{sup nxn}) via the classical Hermite-Fejer interpolation problem.
Block Toeplitz operators with rational symbols
Hwang, In Sung [Department of Mathematics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Woo Young [Department of Mathematics, Seoul National University, Seoul 151-742 (Korea, Republic of)], E-mail: ishwang@skku.edu, E-mail: wylee@math.snu.ac.kr
2008-05-09
In this paper we show that the hyponormality of block Toeplitz operators T{sub {phi}} with matrix-valued rational symbols {phi} in L{sup {infinity}}(C{sup nxn}) is completely determined by the tangential Hermite-Fejer interpolation problem.
Seed conformal blocks in 4D CFT
Echeverri, Alejandro Castedo; Elkhidir, Emtinan; Karateev, Denis; Serone, Marco
2016-02-01
We compute in closed analytical form the minimal set of "seed" conformal blocks associated to the exchange of generic mixed symmetry spinor/tensor operators in an arbitrary representation ( ℓ, overline{ℓ} ) of the Lorentz group in four dimensional conformal field theories. These blocks arise from 4-point functions involving two scalars, one (0, | ℓ - overline{7ell;} |) and one (| ℓ - overline{ℓ} |, 0) spinors or tensors. We directly solve the set of Casimir equations, that can elegantly be written in a compact form for any ( ℓ, overline{ℓ} ), by using an educated ansatz and reducing the problem to an algebraic linear system. Various details on the form of the ansatz have been deduced by using the so called shadow formalism. The complexity of the conformal blocks depends on the value of p = | ℓ - overline{ℓ} | and grows with p, in analogy to what happens to scalar conformal blocks in d even space-time dimensions as d increases. These results open the way to bootstrap 4-point functions involving arbitrary spinor/tensor operators in four dimensional conformal field theories.
Seed conformal blocks in 4D CFT
Echeverri, Alejandro Castedo; Elkhidir, Emtinan; Karateev, Denis [SISSA and INFN,Via Bonomea 265, I-34136 Trieste (Italy); Serone, Marco [SISSA and INFN,Via Bonomea 265, I-34136 Trieste (Italy); ICTP,Strada Costiera 11, I-34151 Trieste (Italy)
2016-02-29
We compute in closed analytical form the minimal set of “seed' conformal blocks associated to the exchange of generic mixed symmetry spinor/tensor operators in an arbitrary representation (ℓ,ℓ̄) of the Lorentz group in four dimensional conformal field theories. These blocks arise from 4-point functions involving two scalars, one (0,|ℓ−ℓ̄|) and one (|ℓ−ℓ̄|,0) spinors or tensors. We directly solve the set of Casimir equations, that can elegantly be written in a compact form for any (ℓ,ℓ̄), by using an educated ansatz and reducing the problem to an algebraic linear system. Various details on the form of the ansatz have been deduced by using the so called shadow formalism. The complexity of the conformal blocks depends on the value of p=|ℓ−ℓ̄| and grows with p, in analogy to what happens to scalar conformal blocks in d even space-time dimensions as d increases. These results open the way to bootstrap 4-point functions involving arbitrary spinor/tensor operators in four dimensional conformal field theories.
Neuraxial block and postoperative epidural analgesia
Leslie, K; McIlroy, D; Kasza, J
2016-01-01
BACKGROUND: We assessed associations between intraoperative neuraxial block and postoperative epidural analgesia, and a composite primary outcome of death or non-fatal myocardial infarction, at 30 days post-randomization in POISE-2 Trial subjects. METHODS: 10 010 high-risk noncardiac surgical pat...
Seed Conformal Blocks in 4D CFT
Echeverri, Alejandro Castedo; Karateev, Denis; Serone, Marco
2016-01-01
We compute in closed analytical form the minimal set of "seed" conformal blocks associated to the exchange of generic mixed symmetry spinor/tensor operators in an arbitrary representation (l,\\bar l) of the Lorentz group in four dimensional conformal field theories. These blocks arise from 4-point functions involving two scalars, one (0,|l-\\bar l|) and one (|l-\\bar l|,0) spinors or tensors. We directly solve the set of Casimir equations, that can elegantly be written in a compact form for any (l,\\bar l), by using an educated ansatz and reducing the problem to an algebraic linear system. Various details on the form of the ansatz have been deduced by using the so called shadow formalism. The complexity of the conformal blocks depends on the value of p=|l-\\bar l | and grows with p, in analogy to what happens to scalar conformal blocks in d even space-time dimensions as d increases. These results open the way to bootstrap 4-point functions involving arbitrary spinor/tensor operators in four dimensional conformal f...
Who Is at Risk for Heart Block?
... degree heart block caused by an overly active vagus nerve. You have one vagus nerve on each side of your body. These nerves ... the way to your abdomen. Activity in the vagus nerve slows the heart rate. Rate This Content: NEXT >> ...
Weight modules over some Block algebras
无
2009-01-01
In this paper, the Harish-Chandra modules and Verma modules over Block algebra L[G] are investigated. More precisely, the irreducibility of the Verma modules over L[G] is completely determined, and the Harish-Chandra modules over L[Z] are classified.
Weight modules over some Block algebras
L(U) RenCai
2009-01-01
In this paper,the Harish-Chandra modules and Verma modules over Block algebra (e)[G]are investigated.More precisely,the irreducibility of the Verma modules over (e)[G]is completely determined,and the Harish-Chandra modules over (e)[Z]are classified.
Iron Blocks of CMS Magnet Barrel Yoke.
2000-01-01
On the occasion of presenting the CMS Award 2000 to Deggendorfer Werft und Eisenbau GmbH the delivered blocks were inspected at CERN Point 5. From left to right: H. Gerwig (CERN, CMS Magnet Barrel Yoke Coordinator), G. Waurick (CERN), F. Leher (DWE, Project Engineer) and W. Schuster (DWE, Project Manager).
Chiral Block Copolymer Structures for Metamaterial Applications
2015-01-27
MONITOR’S REPORT NUMBER(S) AOARD-114078 12. DISTRIBUTION/AVAILABILITY STATEMENT Distribution A: Approved for public release. Distribtion is...researchers focused o synthesis and processing, morphology and physical characterization of chiral block copolymer (BCP) materials. Such materials a...developed a platform process technology that can fabricate novel netwo morphologies from initial bicontinuous cubic phases through supergroup/subgroup
Finding maximum JPEG image block code size
Lakhani, Gopal
2012-07-01
We present a study of JPEG baseline coding. It aims to determine the minimum storage needed to buffer the JPEG Huffman code bits of 8-bit image blocks. Since DC is coded separately, and the encoder represents each AC coefficient by a pair of run-length/AC coefficient level, the net problem is to perform an efficient search for the optimal run-level pair sequence. We formulate it as a two-dimensional, nonlinear, integer programming problem and solve it using a branch-and-bound based search method. We derive two types of constraints to prune the search space. The first one is given as an upper-bound for the sum of squares of AC coefficients of a block, and it is used to discard sequences that cannot represent valid DCT blocks. The second type constraints are based on some interesting properties of the Huffman code table, and these are used to prune sequences that cannot be part of optimal solutions. Our main result is that if the default JPEG compression setting is used, space of minimum of 346 bits and maximum of 433 bits is sufficient to buffer the AC code bits of 8-bit image blocks. Our implementation also pruned the search space extremely well; the first constraint reduced the initial search space of 4 nodes down to less than 2 nodes, and the second set of constraints reduced it further by 97.8%.
Building Blocks for Control System Software
Broenink, Johannes F.; Hilderink, G.H.; Amerongen van, J.; Jonker, B.; Regtien, P.P.L
2001-01-01
Software implementation of control laws for industrial systems seem straightforward, but is not. The computer code stemming from the control laws is mostly not more than 10 to 30% of the total. A building-block approach for embedded control system development is advocated to enable a fast and effici
Nerve injury caused by mandibular block analgesia
Hillerup, S; Jensen, Rigmor H
2006-01-01
: feather light touch, pinprick, sharp/dull discrimination, warm, cold, point location, brush stroke direction, 2-point discrimination and pain perception. Gustation was tested for recognition of sweet, salt, sour and bitter. Mandibular block analgesia causes lingual nerve injury more frequently than...
Block Tridiagonal Matrices in Electronic Structure Calculations
in the Landauer–Büttiker ballistic transport regime. These calculations concentrate on determining the so– called Green’s function matrix, or portions thereof, which is the inverse of a block tridiagonal general complex matrix. To this end, a sequential algorithm based on Gaussian elimination named Sweeps...
Topological structures of boundary value problems in block elements
Babeshko, V. A.; Evdokimova, O. V.; Babeshko, O. M.
2016-10-01
Block structures are considered; a boundary value problem for a system of inhomogeneous partial differential equations with constant coefficients is formulated in each block of a structure. The problem of matching solutions to boundary value problems in blocks with each other by topological study of the properties of solutions in the block structure is examined in the conditions of correct solvability of boundary value problems in blocks of the block structure. Some new properties of solutions to boundary value problems in block structures are found that are important for applications.
On the Marginal Distribution of the Diagonal Blocks in a Blocked Wishart Random Matrix
Kjetil B. Halvorsen
2016-01-01
Full Text Available Let A be a (m1+m2×(m1+m2 blocked Wishart random matrix with diagonal blocks of orders m1×m1 and m2×m2. The goal of the paper is to find the exact marginal distribution of the two diagonal blocks of A. We find an expression for this marginal density involving the matrix-variate generalized hypergeometric function. We became interested in this problem because of an application in spatial interpolation of random fields of positive definite matrices, where this result will be used for parameter estimation, using composite likelihood methods.
Combined KHFAC + DC nerve block without onset or reduced nerve conductivity after block
Franke, Manfred; Vrabec, Tina; Wainright, Jesse; Bhadra, Niloy; Bhadra, Narendra; Kilgore, Kevin
2014-10-01
Objective. Kilohertz frequency alternating current (KHFAC) waveforms have been shown to provide peripheral nerve conductivity block in many acute and chronic animal models. KHFAC nerve block could be used to address multiple disorders caused by neural over-activity, including blocking pain and spasticity. However, one drawback of KHFAC block is a transient activation of nerve fibers during the initiation of the nerve block, called the onset response. The objective of this study is to evaluate the feasibility of using charge balanced direct current (CBDC) waveforms to temporarily block motor nerve conductivity distally to the KHFAC electrodes to mitigate the block onset-response. Approach. A total of eight animals were used in this study. A set of four animals were used to assess feasibility and reproducibility of a combined KHFAC + CBDC block. A following randomized study, conducted on a second set of four animals, compared the onset response resulting from KHFAC alone and combined KHFAC + CBDC waveforms. To quantify the onset, peak forces and the force-time integral were measured during KHFAC block initiation. Nerve conductivity was monitored throughout the study by comparing muscle twitch forces evoked by supra-maximal stimulation proximal and distal to the block electrodes. Each animal of the randomized study received at least 300 s (range: 318-1563 s) of cumulative dc to investigate the impact of combined KHFAC + CBDC on nerve viability. Main results. The peak onset force was reduced significantly from 20.73 N (range: 18.6-26.5 N) with KHFAC alone to 0.45 N (range: 0.2-0.7 N) with the combined CBDC and KHFAC block waveform (p < 0.001). The area under the force curve was reduced from 6.8 Ns (range: 3.5-21.9 Ns) to 0.54 Ns (range: 0.18-0.86 Ns) (p < 0.01). No change in nerve conductivity was observed after application of the combined KHFAC + CBDC block relative to KHFAC waveforms. Significance. The distal application of CBDC can significantly reduce or even
Rizk, Maged K; Tolba, Reda; Kapural, Leonardo; Mitchell, Justin; Lopez, Rocio; Mahboobi, Ramatia; Vrooman, Bruce; Mekhail, Nagy
2012-11-01
Differential thoracic epidural regional block, also known as a differential neural block (DNB), involves the placement of an epidural catheter placed in the thoracic epidural space to achieve appropriate anesthesia in a dermatomal distribution. This is a retrospective case series evaluating how well a DNB may predict success of subsequent visceral blockade in patients with chronic abdominal pain of visceral origin. Of 402 patients who had a DNB performed for unexplained abdominal pain from January 2000 to January 2009, 81 patients were found to have results consistent with visceral pain and thus underwent subsequent visceral blockade. Basic demographic data, years of chronic pain, history of psychosocial issues, initial visual analog scale (VAS) pain score, pain location, and medication usage were documented in our electronic medical record database. Parameters regarding DNB and visceral blocks also were documented. Descriptive statistics were computed for all variables. The positive predictive value (PPV) for DNB for whom visceral block was successful (at least a 50% reduction in VAS) was calculated. Additionally, subjects with successful visceral blocks were compared to those with unsuccessful visceral blocks. All patients with chronic abdominal pain with normal gastrointestinal studies who underwent DNB. Tertiary Outpatient Pain Management Clinic. Retrospective Cohort Study. Mean age of patients was 46 (± 15) years, 73% were female, and median duration of pain was 5 years. 67% of subjects were taking opioid analgesics. PPV of DNB was 70.4%. Only factor found to be statistically significant with visceral block success was baseline VAS with higher scores associated with DNB predictive success (6.8 ± 1.7 vs. 5.5, 1.8; P = 0.004). Use of membrane stabilizing medications was significantly more common in subjects for whom visceral block was not successful (46% vs. 25%; P = 0.058). Area underneath curve (AUC) for VAS was found to be 0.70 (95% CI: 0.57, 0
Using Purpose-Built Functions and Block Hashes to Enable Small Block and Sub-file Forensics
2010-01-01
plagiarism detection engines such as Turnitin can be so successful. Other word sequences are not distinct. “To be or not to be” and “four score and seven...it is no longer distinct. 3.2. The distinct block definition and hypotheses Given the preceding, we propose this definition : Distinct Block... definition ): A block of data thatwill not arise by chance more than once. Distinct blocks need to be manufactured by some random process. Blocks taken froma
Prof. Nar Singh
2016-05-01
Full Text Available In area of video compression, Motion Estimation is one of the most important modules and play an important role to design and implementation of any the video encoder. It consumes more than 85% of video encoding time due to searching of a candidate block in the search window of the reference frame. Various block matching methods have been developed to minimize the search time. In this context, Adaptive Rood Pattern Search is one of the less expensive block matching methods, which is widely acceptable for better Motion Estimation in video data processing. In this paper we have proposed to optimize the macro block size used in adaptive rood pattern search method for improvement in motion estimation.
Solving block linear systems with low-rank off-diagonal blocks is easily parallelizable
Menkov, V. [Indiana Univ., Bloomington, IN (United States)
1996-12-31
An easily and efficiently parallelizable direct method is given for solving a block linear system Bx = y, where B = D + Q is the sum of a non-singular block diagonal matrix D and a matrix Q with low-rank blocks. This implicitly defines a new preconditioning method with an operation count close to the cost of calculating a matrix-vector product Qw for some w, plus at most twice the cost of calculating Qw for some w. When implemented on a parallel machine the processor utilization can be as good as that of those operations. Order estimates are given for the general case, and an implementation is compared to block SSOR preconditioning.
Afridi, Riaz Ahmed Khan; Masood, Tariq; Ahmed, Ehtisham; Obaidullah, Abdul Majeed Jaffar; Alvi, Hamid Fazeel
2014-01-01
Digital nerve blocks are commonly used as effective techniques of anaesthesia to allow a variety of surgical procedures performed on digits. This study was conducted to compare the efficacy of volar subcutaneous single injection block and the traditional dorsal two injections digital block. This randomized controlled trial was conducted at Plastic and Reconstructive Surgery Department, Hayatabad Medical Complex Peshawar from December. 2009-10. A total of 126 patients with pathology distal to the first palmer digital crease divided into two equal groups. Group A received volar subcutaneous digital block while group B dorsal two injections block. Efficacy of digital block was measured in terms of time of onset of anaesthesia, which was the total time duration after administering local anaesthetic to loss of pinprick sensation and total duration of anaesthesia, which was defined as the time period from onset of block (loss of pinprick sensation) till the appearance of pain which required additional local anaesthetic or postoperative analgesia. A total of 126 patients were studied, 63 in each group. Of the total patients, 102 (81%) were male and 24 (19%) female with a mean age of 27 ± 4.2 years (range 17-60 years). The mean time of onset of anaesthesia from injection till the loss of pin prick sensation was 3.32 ± 0.42 minutes for volar single injection group and 4.53 minutes ± 0.57 minutes for dorsal two injections group (p = 0.049). Similarly the mean total duration of anaesthesia for the volar subcutaneous group was 271.9 ± 29.34 minutes while for the dorsal two injections group, it was 229.52 ± 28.82 minutes (p = 0.415). Single injection volar subcutaneous digital block provides faster onset of anaesthesia, produces predictable, consistent dense anaesthesia of all of the fingers with the help of single injection prick.
PhenoBlocks: Phenotype Comparison Visualizations.
Glueck, Michael; Hamilton, Peter; Chevalier, Fanny; Breslav, Simon; Khan, Azam; Wigdor, Daniel; Brudno, Michael
2016-01-01
The differential diagnosis of hereditary disorders is a challenging task for clinicians due to the heterogeneity of phenotypes that can be observed in patients. Existing clinical tools are often text-based and do not emphasize consistency, completeness, or granularity of phenotype reporting. This can impede clinical diagnosis and limit their utility to genetics researchers. Herein, we present PhenoBlocks, a novel visual analytics tool that supports the comparison of phenotypes between patients, or between a patient and the hallmark features of a disorder. An informal evaluation of PhenoBlocks with expert clinicians suggested that the visualization effectively guides the process of differential diagnosis and could reinforce the importance of complete, granular phenotypic reporting.
Infinite-degree-corrected stochastic block model
Herlau, Tue; Schmidt, Mikkel Nørgaard; Mørup, Morten
2014-01-01
In stochastic block models, which are among the most prominent statistical models for cluster analysis of complex networks, clusters are defined as groups of nodes with statistically similar link probabilities within and between groups. A recent extension by Karrer and Newman [Karrer and Newman......, Phys. Rev. E 83, 016107 (2011)] incorporates a node degree correction to model degree heterogeneity within each group. Although this demonstrably leads to better performance on several networks, it is not obvious whether modeling node degree is always appropriate or necessary. We formulate the degree...... corrected stochastic block model as a nonparametric Bayesian model, incorporating a parameter to control the amount of degree correction that can then be inferred from data. Additionally, our formulation yields principled ways of inferring the number of groups as well as predicting missing links...
Osmosis and thermodynamics explained by solute blocking
Nelson, Peter Hugo
2016-01-01
A solute-blocking model is presented that provides a kinetic explanation of osmosis and ideal solution thermodynamics. It validates a diffusive model of osmosis that is distinct from the traditional convective flow model of osmosis. Osmotic equilibrium occurs when the fraction of water molecules in solution matches the fraction of pure water molecules that have enough energy to overcome the pressure difference. Solute-blocking also provides a kinetic explanation for why Raoult's law and the other colligative properties depend on the mole fraction (but not the size) of the solute particles, resulting in a novel kinetic explanation for the entropy of mixing and chemical potential of ideal solutions. Some of its novel predictions have been confirmed, others can be tested experimentally or by simulation.
Porous polymers based on aryleneethynylene building blocks.
Bunz, Uwe H F; Seehafer, Kai; Geyer, Florian L; Bender, Markus; Braun, Ingo; Smarsly, Emanuel; Freudenberg, Jan
2014-09-01
Porous conjugated polymers are synthesized by metal-catalyzed coupling reactions. The progress for porous polymers when planar or tetrahedral building blocks are connected by alkyne units into novel materials is highlighted. The most prominent reaction for the buildup of the microporous alkyne-bridged polymers is the Sonogashira reaction, connecting alkynes to aromatic iodides or bromides. The availability of the building blocks and the potency of the Sonogashira reaction allow preparing a large variety of intrinsically porous polymeric materials, in which rigid struts connect multipronged centers. The microporous polymers are used as catalysts and as storage materials for gases and sensors. Postfunctionalization schemes, understanding of structure-property relationships, and the quest for high porosity are pertinent.
Essential Building Blocks of Human Nature
Frey, Ulrich J; Willführ, Kai P
2011-01-01
To understand why we humans are as we are, it is necessary to look at the essential building blocks that comprise our nature. The foundations of this structure are our evolutionary origins as primates and our social roots. Upon these rest features such as our emotions, language and aesthetic preferences, with our self-perceptions, self-deceptions and thirst for knowledge right at the top. The unifying force holding these blocks together is evolutionary theory. Evolution provides a deeper understanding of human nature and, in particular, of the common roots of these different perspectives. To build a reliable and coherent model of man, leading authors from fields as diverse as primatology, anthropology, neurobiology and philosophy have joined forces to present essays each describing their own expert perspective. Together they provide a convincing and complete picture of our own human nature.
On Combinatorial Expansions of Conformal Blocks
Marshakov, A; Morozov, A
2009-01-01
In a recent paper (arXiv:0906.3219) the representation of Nekrasov partition function in terms of nontrivial two-dimensional conformal field theory has been suggested. For non-vanishing value of the deformation parameter \\epsilon=\\epsilon_1+\\epsilon_2 the instanton partition function is identified with a conformal block of Liouville theory with the central charge c = 1+ 6\\epsilon^2/\\epsilon_1\\epsilon_2. If reversed, this observation means that the universal part of conformal blocks, which is the same for all two-dimensional conformal theories with non-degenerate Virasoro representations, possesses a non-trivial decomposition into sum over sets of the Young diagrams, different from the natural decomposition studied in conformal field theory. We provide some details about this intriguing new development in the simplest case of the four-point correlation functions.
Neurologic complication after anterior sciatic nerve block.
Shah, Shruti; Hadzic, Admir; Vloka, Jerry D; Cafferty, Maureen S; Moucha, Calin S; Santos, Alan C
2005-05-01
The lack of reported complications related to lower extremity peripheral nerve blocks (PNBs) may be related to the relatively infrequent application of these techniques and to the fact that most such events go unpublished. Our current understanding of the factors that lead to neurologic complications after PNBs is limited. This is partly the result of our inability to conduct meaningful retrospective studies because of a lack of standard and objective monitoring and documentation procedures for PNBs. We report a case of permanent injury to the sciatic nerve after sciatic nerve block through the anterior approach and discuss mechanisms that may have led to the injury. Intraneural injection and nerve injury can occur in the absence of pain on injection and it may be heralded by high injection pressure (resistance).
Time and Spacetime: The Crystallizing Block Universe
Ellis, George F R
2009-01-01
The nature of the future is completely different from the nature of the past. When quantum effects are significant, the future shows all the signs of quantum weirdness, including duality, uncertainty, and entanglement. With the passage of time, after the time-irreversible process of state-vector reduction has taken place, the past emerges, with the previous quantum uncertainty replaced by the classical certainty of definite particle identities and states. The present time is where this transition largely takes place, but the process does not take place uniformly: Evidence from delayed choice and related experiments shows that isolated patches of quantum indeterminacy remain, and that their transition from probability to certainty only takes place later. Thus, when quantum effects are significant, the picture of a classical Evolving Block Universe (`EBU') cedes place to one of a Crystallizing Block Universe (`CBU'), which reflects this quantum transition from indeterminacy to certainty, while nevertheless rese...
Osmosis and thermodynamics explained by solute blocking.
Nelson, Peter Hugo
2017-01-01
A solute-blocking model is presented that provides a kinetic explanation of osmosis and ideal solution thermodynamics. It validates a diffusive model of osmosis that is distinct from the traditional convective flow model of osmosis. Osmotic equilibrium occurs when the fraction of water molecules in solution matches the fraction of pure water molecules that have enough energy to overcome the pressure difference. Solute-blocking also provides a kinetic explanation for why Raoult's law and the other colligative properties depend on the mole fraction (but not the size) of the solute particles, resulting in a novel kinetic explanation for the entropy of mixing and chemical potential of ideal solutions. Some of its novel predictions have been confirmed; others can be tested experimentally or by simulation.
Gauge Blocks – A Zombie Technology
Doiron, Ted
2008-01-01
Gauge blocks have been the primary method for disseminating length traceability for over 100 years. Their longevity was based on two things: the relatively low cost of delivering very high accuracy to users, and the technical limitation that the range of high precision gauging systems was very small. While the first reason is still true, the second factor is being displaced by changes in measurement technology since the 1980s. New long range sensors do not require master gauges that are nearly the same length as the part being inspected, and thus one of the primary attributes of gauge blocks, wringing stacks to match the part, is no longer needed. Relaxing the requirement that gauges wring presents an opportunity to develop new types of end standards that would increase the accuracy and usefulness of gauging systems. PMID:27096119
Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles
Bo Liedberg
2013-09-01
Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.
Adductor canal block can result in motor block of the quadriceps muscle.
Chen, Junping; Lesser, Jonathan B; Hadzic, Admir; Reiss, Wojciech; Resta-Flarer, Francesco
2014-01-01
The block of nerves in the adductor canal is considered to cause a sensory block without a motor component. In this report, we describe a case of significant quadriceps muscle weakness after an adductor canal block (ACB). A 65-year-old female patient for ambulatory knee surgery was given an ACB for postoperative pain management. The block was performed under ultrasound guidance at the midthigh level using the transsartorial approach. Twenty milliliters of 0.5% ropivacaine was deposited adjacent to the anterior and posterior areas of the femoral artery. On discharge from the hospital, the patient realized that her thigh muscles were weak and she was unable to extend her leg at the knee. A neuromuscular examination indicated that the patient had no strength in her quadriceps muscle, along with sensory deficit in the medial-anterior lower leg and area in front of knee up to the midthigh. The weakness lasted 20 hours, and the sensory block lasted 48 hours before complete recovery. The optimal level and amount of local anesthetic for adductor canal block are currently not well defined. Proximal spread of local anesthetic and anatomical variation may explain our observation. Several studies have reported that ACB involves no motor blockade. However, our case report illustrates that the ACB can result in clinically significant quadriceps muscle paralysis. This report suggests that patients should be monitored vigilantly for this occurrence to decrease the risk of falls.
Recurrent congenital heart block in neonatal lupus.
Escobar, Maria C; Gómez-Puerta, José A; Albert, Dimpna; Ferrer, Queralt; Girona, Josep
2007-07-01
Congenital heart block (CHB) is the main complication of neonatal lupus (NL) and is strongly associated with the presence of anti-SSA/Ro and anti-SSB/La antibodies. The recurrence of CHB in subsequent pregnancies in mothers with these antibodies is uncommon, occurring in approximately 15% of cases. We describe here a case of recurrent CHB in a previously asymptomatic mother with Sjögren syndrome and discuss the current strategies for the prevention and treatment of CHB in NL.
SODART optical block of the SRG satellite
Christensen, Finn Erland; Frederiksen, P.; Polny, Josef
1998-01-01
This paper describes the design and the successful integration of the optical block of the SODART telescopes to be flown on the Spectrum Roentgen Gamma satellite. The integration involves both the integration of the two high throughput x-ray telescopes as well as the objective crystal spectrometer....... The integrated unit meets all mechanical, thermal and optical specifications and it is now in safe storage in Moscow and awaits further integration procedures with the remaining satellite structure....
General Structures of Block Based Interpolational Function
ZOU LE; TANG SHUO; Ma Fu-ming
2012-01-01
We construct general structures of one and two variable interpolation function,without depending on the existence of divided difference or inverse differences,and we also discuss the block based osculatory interpolation in one variable case.Clearly,our method offers many flexible interpolation schemes for choices.Error terms for the interpolation are determined and numerical examples are given to show the effectiveness of the results.
[Congenital atrioventricular block and maternal autoimmune diseases].
Herreman, G; Sauvaget, F; Généreau, T; Galezowski, N
1990-01-01
Congenital heart block is rare; it is acquired in utero, definitive and, more often than not, complete. It can be diagnosed by the appearance of fetal bradycardia around the 23rd week of gestation, during ultrasonographic monitoring of pregnancy. Heart block is usually associated with the presence of anti-Ro and/or anti-La antibodies in the mother's serum. These maternal immunological abnormalities can be isolated or associated with an autoimmune disease, usually systemic lupus erythematosus, but also Sjögren's syndrome, or more rarely still, an as yet unclassified connective tissue disease. Anti-Ro and anti-La antibodies cross the placental barrier and react with a fetal heart, leading to acute fetal myocarditis by the 17th week of gestation. When severe, it is lethal, otherwise it can result in degeneration and endocardial fibroelastosis, disrupting conduction and leading to congenital heart block. The ideal treatment would be prevention with corticosteroids. When the mother is Ro or La antibody-positive before pregnancy, elimination of these circulating antibodies can be attempted by treatment with 0.5 mg/kg body wt/d of prednisolone for 3 months. If the treatment is successful, corticotherapy can be prescribed early in the pregnancy to try to protect the fetus. However, there is not always a relationship between maternal anti-Ro antibodies and fetal heart block. If the Ro/La antibody-positive woman is already pregnant, but before her 17th week, it is possible to prescribe dexamethasone, which crosses the placenta and remains active, sometimes in association with plasmapheresis.
Floating asphalt blocks of the Dead Sea
Nissenbaum, A. (Weizmann Inst. of Science, Rehovot, Israel); Aizenshtat, Z.; Goldberg, M.
1980-01-01
Large blocks of mineral matter free (less than 0.1%) asphalt are occasionally found floating on the surface of the Dead Sea. Chemical, spectroscopic and isotopic data are given for the asphalt. The source of the asphalt is not accurately known, but presumably it represents mobilization of heavy viscous asphaltic masses at depth below the lake bottom into the floor of the lake. It may be released to the surface by earth tremors.
ISS EPS Orbital Replacement Unit Block Diagrams
Schmitz, Gregory V.
2001-01-01
The attached documents are being provided to Switching Power Magazine for information purposes. This magazine is writing a feature article on the International Space Station Electrical Power System, focusing on the switching power processors. These units include the DC-DC Converter Unit (DDCU), the Bi-directional Charge/Discharge Unit (BCDU), and the Sequential Shunt Unit (SSU). These diagrams are high-level schematics/block diagrams depicting the overall functionality of each unit.
Impedance Matched Absorptive Thermal Blocking Filters
Wollack, E J; Rostem, K; U-Yen, K
2014-01-01
We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match $50\\,\\Omega$ and its response has been validated from 0-to-50\\,GHz. The observed return loss in the 0-to-20\\,GHz design band is greater than $20\\,$dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.
Gauge Blocks – A Zombie Technology
Doiron, Ted
2008-01-01
Gauge blocks have been the primary method for disseminating length traceability for over 100 years. Their longevity was based on two things: the relatively low cost of delivering very high accuracy to users, and the technical limitation that the range of high precision gauging systems was very small. While the first reason is still true, the second factor is being displaced by changes in measurement technology since the 1980s. New long range sensors do not require master gauges that are nearl...
Rectangular Blocks vs Polygonal Walls in Archaeoseismology
Klaus-G. Hinzen
2017-07-01
Full Text Available Collapsed or deformed walls in ancient structures constitute important evidence in archaeoseismology, where damage is interpreted in terms of earthquake ground motion. A large variety of wall types have been developed during the millennia in different cultural backgrounds. Often walls with polygonal-shaped building blocks are regarded as more earthquake-resistant than a wall consisting of rectangular elements and, as is sometimes speculated, that the irregular wall types were intentionally developed for that purpose. We use simply structured discrete element models of four walls with different block geometries, perfect rectangular, an Inka-type structure and two polygonal designs, to test their dynamic behavior. In addition to an analytic calculation of ground motion, we use measured strong motion signals as boundary conditions for the 3D wall models with varying height to width ratios. At peak ground accelerations between 1.0 and 9.0 m/s2 and major frequencies of 0.5 to 3 Hz, numeric experiments with the horizontally applied analytic ground motions result in clear differences in the resistance of the four wall types with the rectangular block wall being most vulnerable. For more complex measured 3D motions the Inka-type wall proves more stable than the rectangular block wall; however, height to width ratio still has equally strong influence on the stability. Internal deformation of non-collapsed walls shows some correlation with the parameters of the driving motion. For simple impulsive ground motions, a peak ground displacement threshold exists between toppling and remaining upright for all four models but peak acceleration cannot be reliably back calculated.
Nanostructured Block Copolymer Coatings for Biofouling Inhibition
2015-06-30
biofouling program contractors. 15. SUBJECT TERMS antifouling; coatings; block copolymers; IR nanoscale imaging ; biocides 16. SECURITY CLASSIFICATION OF...diagnostics and drug delivery. In our scanned probe microscopy studies on collaborator coatings and marine organisms, we have provided teamwork . We have...Studies of Organisms on model fouiants: • H. elegans studies 3. Testing of other contractor materials 4. Imaging technology. We applied our organic
Hyperkalemia-induced complete heart block
Alireza Baratloo
2015-05-01
Full Text Available Background: Potassium, as an extracellular ion, plays an important role in the electrophysiologic function of the myocardium and any change in extracellular concentration of this ion might have a marked impression upon myocyte electrophysiologic gain. High serum potassium levels are thought to impair pulse conduction in Purkinje fibers and ventricles more than that in the Atrioventricular (AV node. Therefore, although complete AV block can occur, it is a rare initial presentation. Case Report: We describe a 62-year-old man with a history of diabetes mellitus, ischemic heart disease and previous Coronary Artery Bypass Graft (CABG, who came to our emergency department due to generalized weakness starting 2 days before admission. The patient also had decreased force in lower limbs, exacerbating from the morning, and was finally diagnosed as a hyperkalemia-induced Complete Heart Block (CHB. It should also be noted that the patient responded dramatically to the administration of 10 mL of 10% calcium gluconate along with external pacing until potassium level correction became effective. Conclusion: In spite of the fact that Hyperkalemia can be associated with frequent Electrocardiogram (ECG abnormality, advanced heart blocks (second- and third-degree AV blocks are usually found only in patients with pre-existing heart failure, conduction abnormalities, or other cardiac diseases. Institution of effective treatment rapidly and forgiveness of traditional non-effective, time consumptive and sometimes risking full-adjustment modalities, such as sodium bicarbonate infusion or exchange resins that prevent their use in the emergent phase, can help minimize patient morbidity and mortality.
Thalamic pain alleviated by stellate ganglion block
Liao, Chenlong; Yang, Min; Liu, Pengfei; Zhong, Wenxiang; Zhang, Wenchuan
2017-01-01
Abstract Rationale: Thalamic pain is a distressing and treatment-resistant type of central post-stroke pain. Although stellate ganglion block is an established intervention used in pain management, its use in the treatment of thalamic pain has never been reported. Patient concerns: A 66-year-old woman presented with a 3-year history of severe intermittent lancinating pain on the right side of the face and the right hand. The pain started from the ulnar side of the right forearm after a mild ischemic stroke in bilateral basal ganglia and left thalamus. Weeks later, the pain extended to the dorsum of the finger tips and the whole palmar surface, becoming more severe. Meanwhile, there was also pain with similar characteristics emerging on her right face, resembling atypical trigeminal neuralgia. Diagnoses: Thalamic pain was diagnosed. Interventions: After refusing the further invasive treatment, she was suggested to try stellate ganglion block. Outcomes: After a 3-day period of pain free (numerical rating scale: 0) postoperatively, she reported moderate to good pain relief with a numerical rating scale of about 3 to 4 lasting 1 month after the first injection. Pain as well as the quality of life was markedly improved with less dose of analgesic agents. Lessons: Stellate ganglion block may be an optional treatment for thalamic pain. PMID:28151918
Renewable Aliphatic Polyester Block Polymer Thermoplastic Elastomers
Martello, Mark Thomas
The performance of thermoplastic elastomers is predicated on their ability to form mechanically tough physically crosslinked elastomeric networks at low temperatures and be able to flow at elevated temperatures. This dissertation focuses on renewable aliphatic polyester block polymers with amorphous polylactide (PLA) and their performance as TPEs. The goal of this work was to enhance the mechanical toughness of PLA containing TPEs; fundamental properties ranging from chemical composition and phase behavior, molecular architecture and melt processability, to melt polymerization strategies were investigated. ABA triblock polymers with PLA end-blocks and rubbery mid-blocks from substituted lactones comprised of poly(6-methyl-epsilon-caprolactone)(PMCL), poly(delta-decalactone), and poly(epsilon-decalactone)(PDL) were produced by sequential ring-opening polymerizations in the bulk. The bulk microstructure of symmetric PLA-PMCL-PLA and PLA-PDL-PLA triblock polymers formed long-range ordered morphologies and the interaction parameter of the repeat units was determined. High molar mass triblocks exhibited elastomeric behavior with good tensile strengths and high elongations. Small triblocks were coupled to produced (PLA-PDL-PLA)n multiblock polymers with high molar mass and accessible order-disorder transitions allowing for melt processing via injection molding. The mechanical toughness of the multiblocks was comparable to the high molar mass triblocks. The controlled polymerization of renewable delta-decalactone was accomplished with an organocatalyst at low temperatures in the bulk to maximize the equilibrium conversion of the monomer.
Høskuldsson, Agnar; Svinning, K.
2006-01-01
Here is presented a unified approach to modelling multi-block regression data. The starting point is a partition of the data X into L data blocks, X = (X-1, X-2,...X-L), and the data Y into M data-blocks, Y = (Y-1, Y-2,...,Y-M). The methods of linear regression, X -> Y, are extended to the case...... of a linear relationship between each X-i and Y-j. X-i -> Y-j. A modelling strategy is used to decide if the residual X-i should take part in the modelling of one or more Y(j)s. At each step the procedure of finding score vectors is based on well-defined optimisation procedures. The principle of optimisation...... is based on that the score vectors should give the sizes of the resulting Y(j)s loading vectors as large as possible. The partition of X and Y are independent of each other. The choice of Y-j can be X-j, Y-i = X-i, thus including the possibility of modelling X -> X-i,i=1,...,L. It is shown how...
Process-Accessible States of Block Copolymers
Sun, De-Wen; Müller, Marcus
2017-02-01
Process-directed self-assembly of block copolymers refers to thermodynamic processes that reproducibly direct the kinetics of structure formation from a starting, unstable state into a selected, metastable mesostructure. We investigate the kinetics of self-assembly of linear A C B triblock copolymers after a rapid transformation of the middle C block from B to A . This prototypical process (e.g., photochemical transformation) converts the initial, equilibrium mesophase of the A B B copolymer into a well-defined but unstable, starting state of the A A B copolymer. The spontaneous structure formation that ensues from this unstable state becomes trapped in a metastable mesostructure, and we systematically explore which metastable mesostructures can be fabricated by varying the block copolymer composition of the initial and final states. In addition to the equilibrium mesophases of linear A B diblock copolymers, this diagram of process-accessible states includes 7 metastable periodic mesostructures, inter alia, Schoen's F-RD periodic minimal surface. Generally, we observe that the final, metastable mesostructure of the A A B copolymer possesses the same symmetry as the initial, equilibrium mesophase of the A B B copolymer.
Block Storage Service: Status and Performance
Van der Ster, Daniel
2014-01-01
This memo summarizes the current status of the Ceph block storage service as it is used for OpenStack Cinder Volumes and Glance Images as of May 2014. We present the block storage activity on the current cluster, measuring IOPS and latencies, and present a cost/benefit analysis of using SSDs to optimize the cost and performance efficiency of the service. During tests in collaboration with IT-CF, we have concluded that by adding SSDs as the synchronous write journals (used to guarantee data durability), we are able increase the IOPS capacity by 4-5 times, at a cost of decreasing the available volume by 20%. Further, the testing has shown that the Ceph implementation is able to operate at the limit of the hardware performance; software-induced performance limitations were not yet observed in either the spinning disk or SSD configurations. In addition, we believe that increasing small write performance with SSDs is applicable only to the block storage use-case; high-bandwidth use-cases such as physics data stora...
Active Block Layout: A High Performance Block Layout Mechanism%Active Block Layout:一种高性能磁盘布局机制
卢军; 卢显良; 罗光春; 韩宏; 魏青松
2003-01-01
The access frequency of different files in file system is dissimilar. If file system can optimize the block lay-out of these hot files which are frequently accessed,the performance of file system will be improved. This paper pre-sents a high performance block layout mechanism: Active Block Layout (ABL). ABL can record the access frequencyof every file in file system and actively optimize the block layout of these hot files by block duplicating. The duplicatedblocks can be placed in the special zone of track,which is called "Cooling Zone". ABL can automatically determine theplacing position and the copy count of the blocks which need to be duplicated. In order to reduce the overhead of blockduplication,this paper also presents a mechanism which uses the potential disk bandwidth to realize the block duplica-tion,and does not obviously degrade the performance of file system.
A POCS-Based Algorithm for Blocking Artifacts Reduction
ZHAO Yi-hong; CHENG Guo-hua; YU Song-yu
2006-01-01
An algorithm for blocking artifacts reduction in DCT domain for block-based image coding was developed. The algorithm is based on the projection onto convex set (POCS) theory. Due to the fact that the DCT characteristics of shifted blocks are different caused by the blocking artifacts, a novel smoothness constraint set and the corresponding projection operator were proposed to reduce the blocking artifacts by discarding the undesired high frequency coefficients in the shifted DCT blocks. The experimental results show that the proposed algorithm outperforms the conventional algorithms in terms of objective quality, subjective quality, and convergence property.