Adaptive channel estimation in WCDMA STTD systems

The receiver performance with the use of a space time transmit diversity (STTD) scheme is more susceptible to the accuracy of channel estimate than that without the use of the STTD scheme since the despreading signals suffer from the effect of crosstalk and the transmit power is equally divided into multiple transmit antennas. As a result, the efficiency of channel estimation in the WCDMA STTD system becomes an important issue more than that in the non-STTD system. In this paper, an adaptive channel estimator (ACE) is designed to mitigate the performance degradation due to inaccurate channel estimation. Numerical results show that the performance improvement significantly increases with the use of the proposed ACE, particularly when the channel condition becomes worse

Design of a Channel-Aware OFDM Transceiver

The transmission performance of an OFDM system can significantly be improved by exploiting the channel characteristics. In this paper, we consider the design of a channel-aware OFDM transceiver whose parameters are adjusted in response to the change of channel condition. To this end, we first estimate the channel state information (CSI), such as the signal to interference power ratio, low order moments of Doppler spectrum and power-delay profile of the channel. The proposed CSI estimator can estimate these CSI parameters altogether in a unique manner by exploiting the autocorrelation properties of the channel impulse response (CIR). Then, we design a CIR estimator and adaptive OFDM modulator that adjust their parameters according to the estimated CSI. Finally, we verify the performance of the proposed OFDM transceiver by computer simulation.This work was in part supported by the Ministry of Information & Communications, Korea, under the Information Technology Research Center (ITRC) Support Program

Optimum pilot pattern for channel estimation in OFDM systems

The performance of channel estimation in orthogonal frequency division multiplexing (OFDM) systems significantly depends on the pilot signal, which is usually scattered in time and frequency domains. For a given pilot density, the authors optimally design the pilot pattern so as to minimize the mean squared error (MSE) of the channel estimate with the use of a general interpolator. The analytic results are verified by computer simulation

Optimum pilot pattern for MMSE channel estimation in single-carrier MIMO systems

The minimum mean squared error (MMSE) channel estimator (CE) can provide receiver performance better than the least square (LS) CE. However, the MMSE CE usually uses a pilot pattern optimally designed for the LS CE. In this paper, we derive an optimum pilot pattern for the MMSE CE in single-carrier MIMO systems assuming that both the transmitter and receiver know the average channel information, such as the channel correlation matrix and signal to interference and noise power ratio. Analytic and simulation results show that the MMSE CE with the use of the proposed pilot pattern can reduce the MSE compared to the use of one optimized for the LS CEThis work was supported (in part) by the Ministry of Information & Communications, Korea, under the Information Technology Research Center (ITRC) Support Program

A Hybrid Channel Estimation Scheme for OFDM Systems

Accurate channel information is indispensable for coherent reception of OFDM signal. Although a Wienertype channel estimation filter (CEF) is known optimum, it is not easily employable due to large implementation complexity. In practice, a moving average (MA)-type CEF is often employed, but it may not provide robust performance to the variation of channel condition. In this paper, we propose a hybrid CEF that takes advantages of both the Wiener and MA CEF, by alternatively employing the CEF according to the channel condition. Simulation results show that the proposed hybrid CEF scheme provides near optimum performance, while significantly reducing the implementation complexity compared to the long tap Wiener CEF

Characteristics of Body Fat, Body Fat Percentage and Other Body Composition for Koreans from KNHANES IV

Accurate measurement of fat mass has become increasingly important with the increasing incidence of obesity. We assessed fat and muscle mass of Koreans with the Korea National Health and Nutrition Examination Survey IV (KNHANES IV). We studied 10,456 subjects (aged 20 to 85 yr; 4,476 men, 5,980 women). Fat and muscle mass were measured by dual-energy x-ray absorptiometry. Reference values of body compositions were obtained using the LMS method. The fat mass index (FMI, body fat mass/height2; kg/m2) of Korean men did not correlate with age (P = 0.452), but those of Korean women (P < 0.001) did. The ratio of percentage of fat in the trunk and legs was positively related with age in both the genders. The appendicular lean mass/height2 (kg/m2) of Korean men was negatively related to age (P < 0.001). In women, this ratio increased with age (P < 0.001). When we defined obesity according to the FMI classification, the rates of obesity were 6.1% (FMI > 9 kg/m2) in men and 2.7% (FMI > 13 kg/m2) in women. It is concluded that the muscle mass decreases and obesity increases with aging in Korean men, whereas both fat mass and obesity increase with aging in Korean women

Outcomes in 102 patients that present to the emergency department with chemotherapy- induced febrile neutropenia Kemoterapi kaynaklı febril nötropeni şikâyetiyle acil servise başvuran 102 hastanın sonuçları

Abstract Objective: Febrile neutropenia (FN) is a major toxic responseto chemotherapy requiring prompt medical attention. There are a limited number of reports on clinical outcome in patients with FN that present to emergency departments. Materials and Methods: We retrospectively evaluated clinical manifestations, therapeutic outcomes, and risk factors for FN in 102 adult patients that presented to the emergency department between 1 January 2006 and 31 March 2009. FN was defined as a body temperature&gt;38°C and a neutrophil count &gt;0.5×10 9 /L on the day of fever onset or the day after. Results: Mean age of the patients was 57 years. Mean absolute neutrophil count (ANC) was 436.8/mm 3 (range: 0-1000/mm 3 ). In all, 23 of the patients (22.5%) died due to complications related to FN. There were not a statistical difference in therapeutic outcome among tumor types, performance status, sex, depth of neutropenia, or time from emergency department presentationto initiation of antibiotic therapy. Age was an important prognostic factor for therapeutic outcome. Mean age of fatal cases was 65 years versus 56 years for non-fatal cases (p=0.016). Bacteremia was noted in 19 patients, 10 (53%) of which died. The mortality rate was significantly higher in thepatients with blood culture-proven bacteria than in those whose blood culture yielded no organism (p=0.013). Conclusion: FN patients that presented to the emergency department had a high mortality rate that increased with age. Given the increasing age of patients diagnosed with cancer as well as therapeutic interventions, the high mortality rate associated withchemotherapy-induced FN in elderly patients requires further study in order to reduce the risk of death. (Turk J Hematol 2011; 28: 193-7

Antitumor activity of sorafenib-incorporated nanoparticles of dextran/poly(dl-lactide-co-glycolide) block copolymer

Sorafenib-incoporated nanoparticles were prepared using a block copolymer that is composed of dextran and poly(DL-lactide-co-glycolide) [DexbLG] for antitumor drug delivery. Sorafenib-incorporated nanoparticles were prepared by a nanoprecipitation-dialysis method. Sorafenib-incorporated DexbLG nanoparticles were uniformly distributed in an aqueous solution regardless of the content of sorafenib. Transmission electron microscopy of the sorafenib-incorporated DexbLG nanoparticles revealed a spherical shape with a diameter < 300 nm. Sorafenib-incorporated DexbLG nanoparticles at a polymer/drug weight ratio of 40:5 showed a relatively uniform size and morphology. Higher initial drug feeding was associated with increased drug content in nanoparticles and in nanoparticle size. A drug release study revealed a decreased drug release rate with increasing drug content. In an in vitro anti-proliferation assay using human cholangiocarcinoma cells, sorafenib-incorporated DexbLG nanoparticles showed a similar antitumor activity as sorafenib. Sorafenib-incorporated DexbLG nanoparticles are promising candidates as vehicles for antitumor drug targeting

Coronary Artery Perforation Following Implantation of a Drug-Eluting Stent Rescued by Deployment of a Covered Stent in Symptomatic Myocardial Bridging

We successfully rescued a patient whose coronary artery perforated following implantation of a drug-eluting stent (DES), by deploying a stent-graft in symptomatic myocardial bridging. Our case demonstrated that coronary perforation could be handled without difficulty when perforated myocardial bridging is confined to the interventricular groov

Perivascular Epithelioid Cell Tumor (PEComa) of Abdominal Cavity from Falciform Ligament: A Case Report

We present a case of perivascular epithelioid cell tumors (PEComas) in the abdominal cavity at the falciform ligament. A 30-yr-old Korean man visited to hospital for the evaluation of a growing, palpable abdominal mass. He had felt the mass growing over 6 months. There was no family or personal history of tuberous sclerosis. The resected specimen showed a mass of 8.0×7.0×5.5 cm in size. Histological examination showed sheets of spindle-to-epithelioid cells with clear-to-eosinophilic cytoplasm. Immunohistochemically, tumor cells were positive for HMB-4 (gp100) and smooth muscle actin. They were also positive for the S-100, which is a marker of neurogenic and melanocytic tumors. Patient was treated with radical resection of tumor without any adjuvant therapy. He is well and on follow-up visits without tumor recurrence