Fixed Block Size Research Articles

Once-weekly albiglutide versus once-daily liraglutide in patients with type 2 diabetes inadequately controlled on oral drugs (HARMONY 7): a randomised, open-label, multicentre, non-inferiority phase 3 study

As new members of a drug class are developed, head-to-head trials are an important strategy to guide personalised treatment decisions. We assessed two glucagon-like peptide-1 receptor agonists, once-weekly albiglutide and once-daily liraglutide, in patients with type 2 diabetes inadequately controlled on oral antidiabetic drugs. We undertook this 32-week, open-label, phase 3 non-inferiority study at 162 sites in eight countries: USA (121 sites), Australia (9 sites), Peru (7 sites), Philippines (7 sites), South Korea (5 sites), UK (5 sites), Israel (4 sites), and Spain (4 sites). 841 adult participants (aged ≥18 years) with inadequately controlled type 2 diabetes and a BMI between 20 and 45 kg/m(2) were enrolled and randomised in a 1:1 ratio to receive albiglutide 30 mg once weekly titrated to 50 mg at week 6, or liraglutide 0·6 mg once daily titrated to 1·2 mg at week 1 and 1·8 mg at week 2. The randomisation schedule was generated by an independent randomisation team by the permuted block method with a fixed block size of 16. Participants and investigators were unmasked to treatment. The primary endpoint was change from baseline in HbA1c for albiglutide versus liraglutide, with a 95% CI non-inferiority upper margin of 0·3%. The primary analysis was by modified intention to treat. The study is registered with ClinicalTrials.gov, number NCT01128894. 422 patients were randomly allocated to the albigultide group and 419 to the liraglutide group; 404 patients in the abliglutide group and 408 in the liraglutide group received the study drugs. The primary endpoint analysis was done on the modified intention-to-treat population, which included 402 participants in the albiglutide group and 403 in the liraglutide group. Model-adjusted change in HbA1c from baseline to week 32 was -0·78% (95% CI -0·87 to -0·69) in the albigludite group and -0·99% (-1·08 to -0·90) in the liraglutide group; treatment difference was 0·21% (0·08-0·34; non-inferiority p value=0·0846). Injection-site reactions occurred in more patients given albiglutide than in those given liraglutide (12·9% vs 5·4%; treatment difference 7·5% [95% CI 3·6-11·4]; p=0·0002), whereas the opposite was the case for gastrointestinal events, which occurred in 49·0% of patients in the liraglutide group versus 35·9% in the albiglutide group (treatment difference -13·1% [95% CI -19·9 to -6·4]; p=0·00013). Patients who received once-daily liraglutide had greater reductions in HbA1c than did those who received once-weekly albiglutide. Participants in the albiglutide group had more injection-site reactions and fewer gastrointestinal events than did those in the liraglutide group. GlaxoSmithKline.

Design and Implementation of Storage System Using Byte-index Chunking Scheme

In this paper, we present an enhanced storage system that supports Byte-index chunking algorithm. The storage system aims to provide efficient data deduplication with high performance and to be performed in rapid time. We describe the overall procedure of Byteindex chunking based storage system including read/write procedure and how the system works. The key idea of Byte-index chunking is to adapt fixed-size block chunk scheme which are distributed to “Index-table” by chunk’s both side boundary values. We have found that Byte-index chunking in storage system provides high performance compared with other chunking schemes. Experiments result shows that the storage system with Byte-index chunking compresses overall data with high deduplication capability and reduce the speed of file processing.

Image Compression based on Quadtree and Polynomial

In this paper, an efficient image compression scheme is introduced, it is based on partitioning the image into blocks of variable sizes according to its locally changing image characteristics and then using the polynomial approximation to decompose image signal with less compressed information required compared to traditional predictive coding techniques, finally Huffman coding utilized to improve compression performance rate. The test results indicate that the suggested method can lead to promising performance due to simplicity and efficiency in terms of overcoming the limitations of predictive coding and fixed block size.

The Asymptotic Existence of Group Divisible ‐Designs of Large Order with Index One

AbstractThe following result gives the answer to the question of whether for a fixed number of groups u and fixed block size k a group divisible t‐design of group type with block size k and index one exists for sufficiently large m if the necessary arithmetic conditions are satisfied. Let k and u be positive integers, . Then there exists an integer such that there exists a group divisible t‐design of group type with block size k and index one for any integer satisfying the necessary arithmetic conditions urn:x-wiley:10638539:media:jcd21365:jcd21365-math-0007The case of this theorem gives an existence theorem for transversal t‐designs of large order, which was previously proved by J. L. Blanchard in an unpublished manuscript.

A highly robust two-stage Contourlet-based digital image watermarking method

In this paper we propose a blind and highly robust watermarking method consisting of two embedding stages. In the first stage, the odd description of image is divided into non-overlapped fixed size blocks and the signature (watermark) is embedded in the high frequency component of the Contourlet transform (CT) of the blocks. In the second stage, the signature is embedded in the low frequency component of the global CT of the image. The main issue associated with two-stage blind watermarking is the selection of the less affected signature among the two embedded signatures. In this paper a measure is introduced to decide between the two extracted signatures. Simulation results indicate that the proposed method achieves higher robustness compared to other known watermarking methods. Moreover, since watermark is embedded in the local as well as global CT coefficients of two different frequency bands, the proposed method is robust against a wide range of attacks. This is due to the fact that most of the attacks affect either a specific frequency band or a specific location in the watermarked image.

압축 센싱의 성능 향상을 위한 가변 블록 크기 기술

기존의 블록 기반 압축 센싱은 고정 블록 크기를 사용하여 신호를 복원하며, 영역별 신호의 특성에 적합한 블록 크기를 사용하지 못하여 복원 성능이 저하된다. 본 논문에서는 이 문제를 해결하기 위하여 블록 기반 압축 센싱에서 신호의 특성에 따라 블록 크기를 가변적으로 결정하여 복원 신호의 품질을 향상시키는 가변 블록 크기 기술을 제안한다. 제안한 방법은 여러 블록 크기로 신호를 복원하고, 프레임별로 각 복원한 신호의 자기 상관도를 측정하여 신호의 특성을 확인하고, 프레임의 블록 크기를 결정한다. 동일한 측정 데이터에 대하여 제안한 가변 블록 크기 방법이 기존의 고정 블록 크기 방법에 비하여 향상된 품질의 신호를 복원하는 것을 확인하였다.

Optical flow estimation for motion-compensated compression

The computation of optical flow within an image sequence is one of the most widely used techniques in computer vision. In this paper, we present a new approach to estimate the velocity field for motion-compensated compression. It is derived by a nonlinear system using the direct temporal integral of the brightness conservation constraint equation or the Displaced Frame Difference (DFD) equation. To solve the nonlinear system of equations, an adaptive framework is used, which employs velocity field modeling, a nonlinear least-squares model, Gauss–Newton and Levenberg–Marquardt techniques, and an algorithm of the progressive relaxation of the over-constraint. The three criteria by which successful motion-compensated compression is judged are 1.) The fidelity with which the estimated optical flow matches the ground truth motion, 2.) The relative absence of artifacts and “dirty window” effects for frame interpolation, and 3.) The cost to code the motion vector field. We base our estimated flow field on a single minimized target function, which leads to motion-compensated predictions without incurring penalties in any of these three criteria. In particular, we compare our proposed algorithm results with those from Block-Matching Algorithms (BMA), and show that with nearly the same number of displacement vectors per fixed block size, the performance of our algorithm exceeds that of BMA in all the three above points. We also test the algorithm on synthetic and natural image sequences, and use it to demonstrate applications for motion-compensated compression.

Space savings and design considerations in variable length deduplication

Explosion of data growth and duplication of data in enterprises has led to the deployment of a variety of deduplication technologies. However not all deduplication technologies serve the needs of every workload. Most prior research in deduplication concentrates on fixed block size (or variable block size at a fixed block boundary) deduplication which provides sub-optimal space efficiency in workloads where the duplicate data is not block aligned. Workloads also differ in the nature of operations and their priorities thereby affecting the choice of the right flavor of deduplication. Object workloads for instance, hold multiple versions of archived documents that have a high degree of duplicate data. They are also write-once read-many in nature and follow a whole object GET, PUT and DELETE model and would be better served by a deduplication strategy that takes care of nonblock aligned changes to data. In this paper, we describe and evaluate a hybrid of a variable length and block based deduplication that is hierarchical in nature. We are motivated by the following insights from real world data: (a) object workload applications do not do in-place modification of data and hence new versions of objects are written again as a whole (b) significant amount of data among different versions of the same object is shareable but the changes are usually not block aligned. While the second point is the basis for variable length technique, both the above insights motivate our hierarchical deduplication strategy. We show through experiments with production data-sets from enterprise environments that this provides up to twice the space savings compared to a fixed block deduplication.

Cipher feedback mode under go‐back‐N and selective‐reject protocols in error channels

ABSTRACTTo produce ciphertexts, two modes of encryption are applied—block ciphers, which encrypt a fixed size block of plaintext at a time, and stream ciphers, which encrypt stream data, one or more bits at a time. As one of stream ciphers, the cipher feedback (CFB) mode is implemented by a block cipher via multiple stages, and in each stage, 1 bit or a number of bits of plaintext are encrypted at a time. Throughout this paper, the study will focus upon the error performance of the stream‐based CFB under two sliding‐window protocols, go‐back‐N and selective‐reject, in an error channel in terms of throughput. We model the performance of the CFB in terms of application‐level throughput and derive the number of stages needed to achieve the optimal throughput, under a given error rate in an error channel. Copyright © 2012 John Wiley & Sons, Ltd.

Effects of exercise on kidney function among non-diabetic patients with hypertension and renal disease: randomized controlled trial

BackgroundChronic kidney disease is an important public health threat. Such patients present high morbidity and mortality due to cardiovascular disease, with low quality of life and survival, and also high expenditure resulting from the treatment. Arterial hypertension is both a cause and a complication of kidney disease; also, arterial hypertension is a risk factor for cardiovascular disease among patients with kidney diseases. There is some evidence that exercise interventions may be beneficial to chronic kidney disease patients, but previous studies included only end-stage patients, i.e. those undergoing dialysis. This study aims to evaluate the effect of exercise on kidney function, quality of life and other risk factors for cardiovascular disease among non-diabetic chronic hypertensive kidney disease patients who are not undergoing dialysis.MethodsThe participants will be located through screening hypertensive patients attended within the public healthcare network in Pelotas, a city in south of Brazil. Eligible individuals will be those with glomerular filtration rate between 15 and 59 ml/min x 1.73 m2. The randomization will be done in fixed-size blocks of six individuals such that 75 participants will be allocated to each group. At baseline, information on demographic, socioeconomic, behavioral, anthropometric, blood pressure and quality-of-life variables will be collected, and laboratory tests will be performed. The intervention will consist of three weekly physical exercise sessions lasting 60–75 minutes each, with a total duration of 16 weeks. The outcomes will be the kidney function progression rate, quality of life, blood pressure, lipid profile, hemoglobin level, ultrasensitive C-reactive protein level, and ankle-arm index. The patients in both groups (intervention and control) will be reassessed and compared partway through the study (8th week), at the end of the intervention (16th week) and in the 8th week after the end of the intervention.DiscussionThere is still a scarcity of data relating to the effect of physical exercise among the most numerous group of individuals with kidney disease, i.e. patients undergoing conservative treatment. In particular, there is a lack of randomized controlled studies. This study will help fill this gap.

Need for exercise among patients with hypertension and renal disease (Nephros trial) randomized controlled trial: preliminary results

1. Jaber BL, Madias NE. Progression of chronic kidney disease: can it be prevented or arrested? Am J Med. 2005; 118:1323-30. 2. Glassock RJ, Winearls C. Ageing and the glomerular filtration rate: truths and consequences. Trans Am Clin Climatol Assoc. 2009; 120:419-28. 3.. Stengel B, Tarver-Carr ME, Powe NR, Eberhardt MS, Brancati FL. Lifestyle factors, obesity and the risk of chronic kidney disease. Epidemiology. 2003; 14:479-87. 4. Robinson-Cohen C, Katz R, Mozaffarian D, Dalrymple LS, de Boer I, Sarnak M, et al. Physical activity and rapid decline in kidney function among older adults. Arch Intern Med. 2009; 169:2116-23. 5. Johansen KL and Painter P. Exercise in individuals with CKD. Am J Kidney Dis 2012; 59(1): 126-134. The study has not yet been finalized, these patients should be evaluated after eight weeks of the end of the intervention. The study protocol suggests a sample of 60 patients in each group, whose goal is intended to be reached later this year. Perhaps this is why some results were not different between groups, by the lack of power. However, at this point, the physical capacity tests already have shown a significant beneficial effect of exercise in this group of patients. These tests aimed at assessing dynamic balance, which is important in tasks that require quick maneuvering, such as go to the bathroom or answer the phone. There is still a scarcity of data relating to the effect of physical exercise among the most numerous group of individuals with kidney disease i.e. patients undergoing conservative treatment. In particular, there is a lack of randomized controlled studies. This study will help fill this gap. REFERENCES: Chronic kidney disease is an important public health threat. Such patients present high morbidity and mortality. There is some evidence that exercise interventions may be beneficial to chronic kidney disease patients, but previous studies included only end-stage patients, which are submitted to the dialysis treatment. This study aims to evaluate the effect of exercise on kidney function and other risk factors for cardiovascular disease among patients with chronic hypertensive kidney disease who are not undergoing dialysis. The participants were located through screening of hypertensive patients attended within the public healthcare. Eligible individuals were those with low glomerular filtration rate, measured by MDRD. The randomization was done in fixed-size blocks of six individuals. At baseline, informations on demographic and socioeconomic characteristics, behavioral, anthropometric measures, blood pressure and quality-of-life were collected, also laboratory tests were performed. The intervention consisted of three weekly physical exercise sessions, lasting 60 minutes each, with a total duration of 16 weeks. The patients in both groups (intervention and control) were evaluated at the end of the intervention (16th week) and will be reassessed in the 8th week after termination.The outcomes were kidney function progression rate, functional capacity, blood pressure and laboratory. The t test was used. A two-tailed significance was level of 5%. The analyses were of intention to treat.

A large order asymptotic existence theorem for group divisible 3-designs with index one

In this paper we prove that group divisible 3-designs exist for sufficiently large order with a fixed number of groups, fixed block size and index one, assuming that the necessary arithmetic conditions are satisfied. Let k and u be positive integers, 3≤k≤u. Then there exists an integer m0=m0(k,u) such that there exists a group divisible 3-design of group type mu with block size k and index one for any integer m≥m0 satisfying the necessary arithmetic conditions 1.m(u−2)≡0mod(k−2),2.m2(u−1)(u−2)≡0mod(k−1)(k−2),3.m3u(u−1)(u−2)≡0modk(k−1)(k−2).

Low Power H.264 Video Compression Achitecture for Mobile Communication

This paper presents a method to reduce the computation and memory access for variable block size motion estimation (ME) using pixel truncation. Previous work has focused on implementing pixel truncation using a fixed-block size(16×16 pixels) ME. However, pixel truncation fails to give satisfactory results for smaller block partitions. In this paper, we analyze the effect of truncating pixels for smaller block partitions and propose a method to improve the frame prediction. Our method is able to reduce the total computation and memory access compared to conventional full-search method without significantly degrading picture quality. With unique data arrangement, the proposed architectures are able to saveup to 53% energy compared to the conventional full-search architecture. This makes such architectures attractive for H.264application in future mobile devices. Keywords- Low-power design, motion estimation (ME), video coding, VLSI architecture.

High Efficiency Architecture Design of Real-Time QFHD for H.264/AVC Fast Block Motion Estimation

Motion estimation (ME) in the MPEG-4 AVC/JVT/H.264 video coding standard employs seven permitted block sizes to improve the rate-distortion performance. This novel feature achieves significant coding gain over coding a macroblock using the fixed block size. However, ME is computationally intensive with the complexity increasing linearly with the number of the allowed block sizes. This paper presents an architecture for a combined fast ME algorithm with the predict hexagon search (PHS) and the edge information mode decision (EIMD). The EIMD algorithm utilizes edge information to predict the best block size quickly and precisely. The PHS algorithm searches the best motion vector efficiently. The analytical results reveal that the EIMD+PHS algorithm is 2.4-25 times faster than other popular fast ME algorithms. Additionally, the EIMD+PHS algorithm is 600-2000 times faster than JM10.2, and the peak signal-to-noise ratio degradation is less than 0.15 dB. The proposed architecture applies a large search range and low operation frequency as compared with other popular ME architectures. The proposed architecture only needs 19.4 MHz operating frequency to achieve real-time execution for the general specification of the standard-definition television (720 × 480) used with four reference frames and the search range of 256 × 256. The proposed architecture only requires 116.6 MHz operating frequency to achieve real-time execution for the ultrahigh specification of the quad full high definition (3840 × 2160) used with one reference frame and the search range of 256 × 256. The gate count of the proposed architecture is 300 K, and the memory usage is 12.6 kB.

Relative Lempel-Ziv factorization for efficient storage and retrieval of web collections

Compression techniques that support fast random access are a core component of any information system. Current state-of-the-art methods group documents into fixed-sized blocks and compress each block with a general-purpose adaptive algorithm such as gzip. Random access to a specific document then requires decompression of a block. The choice of block size is critical: it trades between compression effectiveness and document retrieval times. In this paper we present a scalable compression method for large document collections that allows fast random access. We build a representative sample of the collection and use it as a dictionary in a LZ77-like encoding of the rest of the collection, relative to the dictionary. We demonstrate on large collections, that using a dictionary as small as 0.1% of the collection size, our algorithm is dramatically faster than previous methods, and in general gives much better compression.

A robust detection algorithm for copy-move forgery in digital images

With the availability of the powerful editing software and sophisticated digital cameras, region duplication is becoming more and more popular in image manipulation where part of an image is pasted to another location to conceal undesirable objects. Most existing techniques to detect such tampering are mainly at the cost of higher computational complexity. In this paper, we present an efficient and robust approach to detect such specific artifact. Firstly, the original image is divided into fixed-size blocks, and discrete cosine transform (DCT) is applied to each block, thus, the DCT coefficients represent each block. Secondly, each cosine transformed block is represented by a circle block and four features are extracted to reduce the dimension of each block. Finally, the feature vectors are lexicographically sorted, and duplicated image blocks will be matched by a preset threshold value. In order to make the algorithm more robust, some parameters are proposed to remove the wrong similar blocks. Experiment results show that our proposed scheme is not only robust to multiple copy-move forgery, but also to blurring or nosing adding and with low computational complexity.

The asymptotic existence of group divisible designs of large order with index one

This paper gives the answer to a question of R.M. Wilson regarding the existence of group divisible designs of large order. Let k and u be positive integers such that 2 ⩽ k ⩽ u . Then there exists an integer m 0 = m 0 ( k , u ) such that there exists a group divisible design of group type m u with block size k and index one for any integer m ⩾ m 0 satisfying the necessary arithmetic conditions 1. m ( u − 1 ) ≡ 0 mod ( k − 1 ) , 2. m 2 u ( u − 1 ) ≡ 0 mod k ( k − 1 ) . This paper also presents a large-index asymptotic existence theorem for group divisible t-designs with a fixed number of groups, fixed group size and fixed block size.

Secret image sharing with authentication-chaining and dynamic embedding

Abstract A popular technique to share a secret image among n participants is to divide it first into some shadow images and then embed the shadows in n”cover” images. The resulting “stego” images, which contain the embedded data, are distributed among intended recipients. In order not to attract any attacker’s attention, it is important to apply a suitable embedding such that high quality stego images are produced. Moreover, to ensure the integrity of stego data, a robust authentication mechanism which can detect tampering with high probability should be implemented. Recently, a series of papers ( Lin and Tsai, 2004; Yang et al., 2007; Chang et al., 2008; Yang and Ciou, 2009) have considered polynomial-based secret image sharing with steganography and authentication. The embedding technique employed in all these papers is static, i.e. hidden bits are embedded in predetermined fixed-size blocks of each cover image. It is therefore possible that all the hidden data is replaced in only a subset of blocks of cover images while other blocks remain intact. As for authentication, the best of these schemes detects a tampered stego block with probability 15/16, however, since this is obtained at the cost of using 4 authentication bits per block, the visual quality of stego images is seriously degraded. In this paper, we propose a novel polynomial-based secret image sharing scheme with two achievements. First, a new embedding is proposed so that the block size is determined dynamically according to the size of hidden data and therefore, all the capacity of cover images is used for data hiding. Second, we introduce a new authentication-chaining method which achieves 15/16 as its tamper-detection ability while using only 2 authentication bits. Experimental results are provided to confirm the theory.

An intelligent watermarking method based on particle swarm optimization

Meerwald, Koidl, and Uhl (2009) pointed out that the method proposed in Lin et al. (2008) exists potential insecurity. This paper proposes an intelligent watermarking by invoking particle swarm optimization (PSO) technique in wavelet domain to overcome the revealed insecurity issue, furthermore resolve the conflict between imperceptibility and robustness of watermarking. In the proposed method, PSO is fused with the method proposed in Lin et al. (2008) (denoted SDWCQ) to avoid potentially insecurity in Lin et al. (2008). That is, the method of using the fixed block size in one subband and the permutation is unable to disguise which coefficients make up a block. The attacker can utilize the insecure property and analyze the significant difference between bipolar watermarks in Lin et al. (2008) to detect the embedded blocks, furthermore modify the significant difference, and result in unable to extract the watermark. In this paper, coefficients are randomly selected from different subbands to make up a block to promote the disguise. Performance analysis shows that the proposed algorithm obviously outperforms SDWCQ which does not use PSO.

Low power VLSI architectures for one bit transformation based fast motion estimation

In the present paper, architectures implementing fixed block size and variable block size (VBS) motion estimation (ME) algorithms on one bit transformed (1-BT) image frames have been presented. The proposed architectures perform ME by applying diamond search (DS) algorithm on 1-BT image frames. The 1-BT based ME is usually performed by applying full search (FS) algorithm. Our simulation results reveal that the application of DS on 1-BT based ME can significantly reduce the computational complexity which is observed in FS based 1-BT ME at a tolerable degradation in the quality. In terms of latency, the architectures have been shown to be superior to several other 1-BT ME architectures. The presented DS based 1-BT ME architectures have succeeded in reducing the minimum clock frequency required to process a video sequence with a given frame size and frame rate, which in turn reduces the overall power consumption compared with other ME architectures. In particular, for processing SDTV sequences (1280×720 @ 30 fps), the power consumption by the proposed VBS ME architecture is reduced by at least 41% compared to the other 1-BT based ME architectures available in literature. The proposed architectures are therefore, considered suitable for low-power portable video applications typically operated by battery power.