Quantization Error Correction Schemes for Lattice-Reduction Aided MIMO Detectors

Lattice reduction aided (LRA) linear detectors have been known to achieve near optimal performance at low complexity. However, one weakness of LRA detector is that the quantization step in LRA detector is not optimal. Based on simulation results, we show that most of detection errors in LRA linear detectors are due to quantization errors. We then propose two methods to correct the quantization errors. In the first method, sphere detectors are introduced to correct quantization errors at low additional complexity. As a second approach, we propose a list quantization scheme which can generate a list of candidate symbols from the original LRA estimated symbols. From these listed symbols, decisions are made according to the minimum Euclidean distance between the received and estimated points. It is shown by simulations that both methods provide significant BER performance improvements with only a small additional complexity

Life Style Factors Influencing Serum Pepsinogen Levels in Healthy Japanese: a Prospective Study

Background: Gastric cancer mass screening using serum pepsinogen has been recognized and several advantages of this methods over photofluorography have been shown by previous study. Aims: To determine the factors influence the serum pepsinogen levels in healthy subjects. Subjects & Methods: One thousand and one hundred fourteen subjects who were screened for gastric cancer as part of a periodic health check. Blood samples were taken after fasting and stored below –20 ° C, until pepsinogen levels were assayed. Results: The subjects consist of 338 males (mean age 52.6+14.0) and 776 females (mean age 49.0+11.9). Age ranges from 19 to 81 years. The overall prevalence of chronic atrophic gastritis using a criterion PG I £ 70 hg/ml and PG I/II ratio £ 3.0 was 21.99 % in 1996 and 23.97 % in 2000. Bivariate analysis revealed a significant association between age, more salt consumption, fish favorable over meat and less than three time meal intake covariates with the lowering of PG I/II ratio. Smoking, drinking, BMI, weight and gender did not affect the changes of PG I/II ratio. Conclusion: Age and more salt consumption covariates have a strongest association with the decreased of PG I/II by multivariate analysis

Lattice-Reduction-Aided Detection with Successive Interference Cancelation for Multiuser Space-Time Block Coded Systems

Effective detectors with low-complexity are considered for the Alamouti’s multiuser space-time block coded (STBC) systems. Viewing the noiseless received signals from Q users as a lattice with basis vectors being the columns of the total channel matrix H, we apply lattice reduction to transform the original basis into a nearly orthogonal one which improves the decision regions against noise. Then, linear detection using zero-forcing (ZF) and minimum-mean-square-error (MMSE) methods is performed on the transformed basis to detect transmitted signals from the Q users. These lattice-reduction-aided (LRA) linear detectors significantly improve BER of the linear detectors and, more importantly, allow us to achieve full diversity at high Eb/N0 regions

Expression of Cyclooxygenase Enhances Tumor Invasion and Metastasis in Human Gastric Carcinoma

Background: Expression of COX-2 in vitro has been shown to have a number of cellular effects including increasing proliferation, reducing apoptosis promoting angiogenesis, decreasing E-cadherin expression and increasing invasive/metastatic potential. Aims: To determine the role of COX-2 in the development and metastasis potential of gastric carcinoma in human subjects. Methods: Tissue samples were obtained from surgically removed specimens of 48 patients with primary gastric adenocarcinoma who underwent gastrectomy from January 1998 to December 1999. The specimens were stained for HE while COX-2 expressions in cancer fold and antrum site were evaluated immunohistochemically. Expression of COX-2 was defined as positive when either one of cancer lesion or antrum site showed immunoreactivity. Results: Preliminary result from 12 out of 48 cases, COX-2 immunoreactivity was detected in 50% (6 of 12 specimens). Expression of COX-2 were more frequent in tumor with serosal invasion (5 of 6 specimens), lymph node metastases (3 of 3 specimens), tumor size more than 4 cm and were significant, statistically (p<0.05). The expression of COX-2 in well differential carcinoma type was similar with in poorly differentiated carcinoma type. Conclusion: COX-2 expression in gastric carcinoma tissue is correlated closely with tumor size, serosal invasion and lymph node metastases, indicating that COX-2 is involved in the growth and metastases of gastric carcinoma

Simplified Dynamic Phantom for Pediatric Renography: A Description of Instrument and Its Performance

Objective(s): Renography is used for the diagnostic evaluation of pediatric patients with a suspected obstruction of urinary tract or impaired renal function. The recommended dose for children have been released by the European Association of Nuclear Medicine, Society of Nuclear Medicine and Molecular Imaging, and Japanese Society of Nuclear Medicine. Since acquisition counts in dynamic scintigraphy are affected by the administered doses and sensitivity of the scintillation camera, the scan procedure should be determined independently. In this study, we constructed simplified dynamic phantom imitating pediatric renography and tested its performance.Methods: Simplified dynamic phantom consisted of three components (i.e.,infusion, imitated kidney, and drainage sections). The infusion rates (mL/min) were determined by comparing the time activity curves obtained from patientswith normal renal function. The time-points of the maximum counts (Tmax), as well as the two-thirds and one-half of the maximum counts (T2/3 and T1/2) were measured in different doses using the phantom with the best-match infusion rateand duration, and low-energy general-purpose (LEGP) or low-energy highresolution (LEHR) collimators and applying different attenuations.Results: The best-match infusion rates of the phantom to imitate the time activity curve of the normal renal function were 42.0, 1.0, 0.6, and 0.3 mL/min in the arterial, secretory, early-excretory, and late-excretory phases, respectively. When 30 MBq, LEHR collimator and non-water-equivalent phantom were applied, Tmax, T2/3, and T1/2 were 242±15.3, 220±10.0 and 317±25.2 seconds, respectively. Using LEGP collimator and (3 MBq of activity) 5-cm water-equivalent phantom, Tmax, T2/3, and T1/2 values were estimated as 242±5.8, 213±11.5, and 310±17.3 sec, respectively.Conclusion: Our simplified dynamic phantom for pediatric renography could imitate the time activity curves obtained from patients with normal renal function. Tmax, T2/3, and T1/2 could be measured under various settings of dose,collimator, and tissue attenuation

ヒドロコルチゾン投与は日本人心肺停止患者の生存率改善に関連する

There are few reports on hydrocortisone administration after cardiac arrest, and those that have been published included few subjects. This study aimed to evaluate the effect of hydrocortisone administration on the outcomes of patients who experienced cardiac arrest. We investigated the survival discharge rates and the length of hospital stay from cardiac arrest to discharge, stratified by use of hydrocortisone, using a Japanese health-insurance claims dataset that covers approximately 2% of the Japanese population. The study included the data of 2233 subjects who experienced either in-hospital or out-of-hospital cardiac arrest between January 2005 and May 2014. These patients were divided into two groups, based on the administration of hydrocortisone. We adjusted the baseline characteristics, medical treatment, and drug administration data of the two groups using propensity scores obtained via the inverse probability of treatment weighted method. The hydrocortisone group had a significantly higher survival discharge rate (13/61 [21.1%] vs. 240/2172 [11.0%], adjusted odds ratio: 4.2, 95% CI: 1.60–10.98, p = 0.004). In addition, the administration of hydrocortisone was independent predictor of survival to discharge (hazard ratio: 4.6, p < 0.001). The results demonstrate a correlation between hydrocortisone administration and the high rates of survival to discharge

Gram-Schmidt Combined LLL Lattice-Reduction Aided Detection in MIMO Systems

This paper proposes an improved lattice-reduction aided (LRA) MMSE detection scheme, based on the Gram-Schmidt (GS) procedure. The proposed scheme reduces the column vectors of the MIMO channel matrix, by using the LLL algorithm followed by the GS procedure in order to transform the channel matrix into a new one which has mutually purely orthogonal column vectors. Compared to the conventional LRA MMSE detector, the proposed detector achieves a very good BER performance, almost equivalent to those using the ML detector in the 4 × 4 MIMO system at the cost of a slightly larger computational complexity

Studies of the Mechanical Properties of Sea Ice ⅩⅠ : The Flexural Strength of Sea Ice in situ

International Conference on Low Temperature Science. I. Conference on Physics of Snow and Ice, II. Conference on Cryobiology. (August, 14-19, 1966, Sapporo, Japan