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Background/Aims: To prevent hypocalcemia after parathyroidectomy (PTX), parenteral calcium is required in addition to oral calcitriol and calcium. After switching to oral calcium, patients can be discharged from the hospital. The aim of this study was to analyze the clinical characteristics and outcomes of PTX performed at a single Korean center and to investigate the associated laboratory factors used to analyze the total amount of postoperative calcium required. Methods: We enrolled 91 hemodialysis patients undergoing PTX from November 2003 to December 2011. We collected clinical and laboratory data preoperatively, 12 and 48 hours postoperatively, at discharge, and 3 and 6 months postoperatively. Results: In total, 59 patients underwent PTX with autotransplantation (AT), 6 underwent total PTX without AT, 11 underwent subtotal PTX, and 15 underwent limited PTX. Total PTX without AT showed the lowest recurrence rate. At all postoperative time points, the mean levels of serum calcium, phosphorus, and intact parathyroid hormone (iPTH) decreased significantly, compared with preoperative levels; however, alkaline phosphatase (ALP) increased significantly from 48 hours postoperatively to discharge (p < 0.001). On multiple linear regression analysis, the total amount of injected calcium during hospitalization showed a significant correlation with preoperative ALP (p < 0.001), preoperative iPTH (p = 0.037), and Δphosphorus at 48 hours (p < 0.001). We developed an equation for estimating the total calcium requirement after PTX. Conclusions: Preoperative ALP, preoperative iPTH, and Δphosphorus at 48 hours may be significant factors in estimating the postoperative calcium requirement. The formula for postoperative calcium requirement after PTX may help to predict the duration of postoperative hospitalization.

High-performance pseudorandom number generators (PRNGs) play an important role in a variety of applications like computer simulations, and industrial applications including cryptography. High-quality PRNG can be constructed by employing cellular automata (CA). Advantage of the PRNG that employs CA includes that it is fast and suitable for hardware implementation. In this paper, we propose a two-dimensional (2-D) CA based PRNG. Our scheme uses the structure of programmable CA (PCA) for improving randomness quality. Moreover, for reducing of serial correlations among the produced pseudorandom bits, a consecutive bits replacing spacing technique is proposed. Finally, we provide experimental results to verify the randomness quality using ENT and DIEHARD test suites.

An application of cellular automata (CA) has been proposed for building parallel processing systems, cryptographic hashing functions, and VLSI technology. Recently, Das et al. have reported characterization of reachable/non-reachable CA states. Their algorithm has only offered the characterization under a null boundary CA (NBCA). However, in the simplifications of hardware implementation, a periodic boundary CA (PBCA) is suitable for constructing cost-effective algorithms such as a linear feedback shift register (LFSR) structure because of its circular property. Therefore Kang et al. have provided an algorithm for deciding of group/non-group CA based on periodic boundary condition. However, they did not have provided an algorithm for constructing of group CA rules. Thus, this paper presents an efficient evolutionary algorithm for constructing of group CA rules based on periodic boundary condition. We expect that the proposed algorithm will be efficiently used in variety of applications including cryptography and VLSI technology.

Pseudorandom number generator (PRNG) has been used in a variety of applications like computer simulations, and industrial applications including cryptography. High-quality PRNG can be constructed by employing cellular automata (CA). Advantage of the PRNG that employs CA includes that it is fast and suitable for hardware implementation. In this paper, we propose a two-dimensional (2-D) CA based PRNG. Our scheme uses the structure of programmable CA (PCA) for improving randomness quality. The CA rules used our PRNG are additive rules which has XOR and XNOR logic with a hybrid dependency, only rules 15, 31, 47 and 63. Moreover, for minimising of auto correlations among the produced pseudorandom number blocks, a novel time spacing technique is proposed without a loss of an original cycle length. Finally, we provide experimental results to verify the randomness quality using ENT and DIEHARD test suites.

Cellular automata (CA) have been used for modeling the behavior of complex systems such as the VLSI technology and parallel processing system. Recently, Das et al. have reported the characterization of reachable/non-reachable CA states. Their scheme has only offered characterization under a null boundary CA (NBCA). In the simplifications of hardware implementation, however, a periodic boundary CA (PBCA) is suitable for constructing cost-effective schemes such as a linear feedback shift register (LFSR) structure because of its circular properties. Thus, this paper presents two evolutionary algorithms for the identification of the reachable/non-reachable state and the group/non-group CA based on periodic boundary conditions.

In 2006, Manik et al. proposed a novel remote user authentication scheme using bilinear pairings. Chou et al. identified a weakness in Manik et al.’s scheme and improved the scheme. And besides, Thulasi et al. pointed that both Manik et al.’s and Chou et al.’s schemes are vulnerable to forgery attacks and replay attacks. In this paper, we analyze the previous schemes based on a timestamp and provide further comments and an improved scheme using a nonce. Our scheme also provides mutual authentication between a user and a remote server while the previous schemes only provided unilateral authentication.