Search

Matrix metalloproteinase-9 (MMP-9) is a gelatinase, which is a member of the MMPs family. We know that MMP-9 is not only an important gelatinase to regulate the extracellular matrix balance, but also one of the most closely related proteases to the pathogenesis of intracranial aneurysm. The purpose of this study is to investigate the relationship between MMP-9 gene polymorphism and intracranial aneurysm. In this paper, 98 patients who were admitted to a hospital from 2018 to 2019 were selected as the experimental group and the control group according to the relevant standards of intracranial aneurysms. The MMP-9 positive and MMP-9 absorbance values between the two groups were compared, so as to determine the concentration of MMP-9 between the two groups. In addition, the gene distribution and gene frequency analysis of the C-1562T promoter region of MMP-9 were carried out. The results showed that in the control group, the gene distribution frequency of CC type was 67% that of CT type was 31% that of TT type was 2%, that of the experimental group was 52%, and that of CT type was 44%. The results showed that there was a correlation between MMP-9 gene polymorphism and intracranial aneurysm.

Objective To investigate the effect of supplemental dexmedetomidine in interventional embolism on cerebral oxygen metabolism in patients with intracranial aneurysms. Methods Ninety patients who underwent interventional embolism of intracranial aneurysms were equally divided into Group A and Group B. In Group A, dexmedetomidine was injected intravenously 10 minutes before inducing anesthesia, with a loading dose of 0.6 µg/kg followed by 0.4 µg/kg/hour. Group B received the same amount of normal saline by the same injection method. Heart rate (HR), mean arterial pressure (MAP), arterial–jugular venous oxygen difference [D(a-jv) (O2)], cerebral oxygen extraction [CE (O2)], and intraoperative propofol use were recorded before inducing anesthesia (T0) and at five time points thereafter. Results The amount of propofol in Group A was lower vs Group B. At all five time points after T0, HR, MAP, D(a-jv) (O2), and CE (O2) in Group A were significantly lower vs Group B, with significant differences for jugular venous oxygen saturation (SjvO2) and the oxygen content of the internal jugular vein (CjvO2) between the groups. Conclusion Dexmedetomidine resulted in less intraoperative propofol, lower D(a-jv) (O2) and CE (O2), and improved cerebral oxygen metabolism.

A new method to encrypt a compressed multimedia bit stream, which is the output of any compression system using an entropy coder in the last stage, is proposed in this research. The basic idea is to partition a coded bit stream into random-sized blocks and perform a random rotation in each block. The proposed encryption scheme demands low computational overhead and does not increase the size of compressed bit stream. Security analysis to both the ciphertext-only attack and the known/chosen-plaintext attack shows that the proposed algorithm achieves high security.

An encryption scheme called the Randomized Dictionary Table (RDT), which embeds encryption into the LZ78 data compression method, is proposed and analyzed in this research. The basic idea is to construct multiple dictionaries with a different entry order and then randomly select one dictionary in each compression step according to a pseudo-random sequence. Our scheme incurs light computation overhead to encrypt the compressed data and does not impair the LZ compression ratio. Security analysis demonstrates that the proposed RDT scheme achieves high security strength under both the ciphertext only attack and the known/chosen plaintext attack.

Efficient multimedia encryption algorithms play a key role in multimedia security protection. One algorithm known as the MHT (multiple Huffman tables) method was recently developed by Wu and Kuo (2001; 2000). Although MHT has many desirable advantages, it is vulnerable under the chosen-plaintext attack (CPA). In this work, an enhanced MHT encryption scheme is proposed to remedy this drawback using the idea of key hopping. It is demonstrated by mathematical analysis that our proposed scheme is secure against chosen plaintext attack.

A new paradigm of one-way hash function, called the distance-preserving hash function (DP hash function), is proposed and a soft multimedia content authentication scheme is developed accordingly in this work. The DP hash function has a distinct characteristic from regular hash functions. That is, when it is equipped with a correct key, the difference between two outputs reflects the distance between the corresponding inputs. However, if a wrong key value is used, the DP hash function reduces to a regular one-way hash function. We examine the theoretical aspect of the DP hash function and propose a practical way for its construction. The DP hash value of the multimedia feature vector is used as the authenticator for the corresponding content. By comparing the DP hash of received data and the received DP hash (authenticator), users can obtain the error between the received data and the original data. This error information indicates a degree of authenticity and allows users to render a soft decision rather than an "authentic or non-authentic" hard decision. Such a soft decision is helpful in applications where a small amount of distortion in the target data is acceptable, such as digital audio and video.

Efficient multimedia encryption algorithms are fundamental to multimedia data security because of the massive data size and the need of real-time processing. In this research, we present an efficient encryption scheme, called the RCI-QM coder, which achieves the objective of encryption with a regular QM coder by applying different coding conventions to encode individual symbols according to a statistically random sequence. One main advantage of our scheme is the negligible computation cost associated with encryption. We also demonstrate with cryptanalysis that the security level of our scheme is high enough to thwart most common attacks. The proposed RCI-QM coder is easy to implement in both software and hardware, while providing backward compatibility to the standard QM coder.

Efficient multimedia encryption algorithms play a key role in multimedia security protection. One multimedia encryption algorithm known as the MHT (Multiple Huffman Tables) method was recently developed by Wu and Kuo in [4] and [5]. Even though MHT has many desirable properties, it is vulnerable to the chosen-plaintext attack (CPA). An enhanced MHT algorithm is proposed in this work to overcome this drawback. It is proved mathematically that the proposed algorithm is secure against the chosen plaintext attack.

The robust stabilization problem (RSP) of an interval plant family is considered. By representing the nominal plant with the normalized coprime factorization description, the RSP of interval plant family is converted to a particular H/sub /spl infin// control problem. An analytical formula for calculating the parametric stability radius /spl delta//sub max/ of the closed-loop system consisting of the interval plant family and the H/sub /spl infin// controller is given. Using /spl delta//sub max/, the stability margin /spl epsi//sub IP/, of the closed-loop system, described in terms of the H/sub /spl infin//-norm of the uncertain factors in the NCF description, is calculated. Numerical example shows that /spl epsi//sub IP/ is larger than the stability margin of the general unstructured uncertainties case.

This work investigates the problem of efficient multimedia data encryption. A novel methodology is proposed to achieve encryption by controlling certain operations in the data compression process using a secret key. The new encryption approach consists of two cascaded modules. The first one is called randomized entropy coding (REC) while the second one is called rotation in partitioned bitstream (RPB). By leveraging the structure of the entropy coder, the joint REC/RPB encryption scheme incurs extremely low computational and implementation costs. Security analysis shows that the proposed scheme can withstand the ciphertext-only attack as well as the known/chosen plaintext attack. The efficiency and security of the proposed encryption scheme makes it an ideal choice in secure media applications where a large amount of multimedia data has to be encrypted/decrypted in real time.