Estimation of fast fading channel in impulse noise environment

This paper studies the estimation of fast fading channel in the present of impulse noise. Fast fading channel in wireless communications system is typically modeled as autoregressive (AR) process. Least-square algorithm and Kalman filter are previously proposed for estimating the AR parameters and the channel impulse response respectively using training sequence. The performance of these algorithms, however, is very sensitive to impulse noise. In this paper, a robust Kalman filter and a robust recursive least M-estimate algorithm are employed to jointly estimate the channel impulse response and the AR parameters of fast fading channel under impulse noise. Simulation showed that the proposed algorithms are much less sensitive to impulse noise than the conventional algorithms.published_or_final_versio

Two patient controlled sedation techniques compared using Graseby PCA pump

Abstract no. 17published_or_final_versio

Adenovirus-mediated gene transfer to liver grafts: An improved method to maximize infectivity

Background. Adenoviral gene therapy in liver transplantation has many potential applications, but current vector delivery methods to grafts lack efficiency and require high titers. In this study, we attempted to improve gene delivery efficacy using three different delivery methods to liver grafts with adenoviral vector encoding the LacZ marker gene (AdLacZ). Methods. AdLacZ was delivered to cold preserved rat liver grafts by: (1) continuous perfusion via the portal vein (portal perfusion), (2) continuous perfusion via both the portal vein and hepatic artery (dual perfusion), and (3) trapping viral perfusate in the liver vasculature by clamping outflow (clamp technique). Results. Using 1x109 plaque-forming units of Ad-LacZ (multiplicity of infection of 0.4), transduction rate in 3-hr preserved liver grafts, determined by 5-bromo-4-chromo-3-indolyl-β-D-galactopyranoside staining and β-galactosidase assay 48 hr after transplantation, was best with clamp technique (21.5±2.7% 5-bromo-4-chromo-3-indolyl-β-D- galactopyranoside-positive cells and 81.1±3.6 U/g β-galactosidase), followed by dual perfusion (18.5±1.8%, 66.6±19.4 U/g) and portal perfusion (8.8±2.5%, 19.7±15.4 U/g). Further studies using clamp technique demonstrated a near-maximal gene transfer rate of 30% at multiplicity of infection of 0.4 with prolonged cold ischemia to 18 hr. Transgene expression was stable for 2 weeks and slowly declined to 7.8±12.1% at day 28. Lack of inflammatory response was confirmed by histopathological examination and liver enzymes. Transduction was selectively induced in hepatocytes with nearly no extrahepatic transgene expression in the lung and spleen. Conclusions. The clamp technique provides a highly efficient viral gene delivery method to cold preserved liver grafts. This method offers maximal infectivity of adenoviral vector with minimal technical manipulation

The Hong Kong parking demand study

This paper describes the objectives, methodology, findings, recommendations and implementation programme of a parking demand study which was conducted in Hong Kong during the period 1993-1995. The study comprises extensive surveys to establish parking characteristics and parking inventory, a stated preference survey to estimate the influence of parking space availability on modal choice, development of parking demand models for private cars and goods vehicles, identification of problems related to parking, and formulation of remedial measures.published_or_final_versio

A multistage filterbank-based channelizer and its multiplier-less realization

This paper proposes a multistage filterbank-based channelizer for software radio base stations. The proposed channelizer is capable of receiving channels with potentially different bandwidths as required in a multi-standard cellular based station. It consists of multiple stages of DFT filter banks and efficient sample rate changers. The front-end DFT filter bank of the channelizer has a fixed number of channels but the passband supports overlap with each other. The received signals selected by a given output of this filter bank are fed into sample rate changers so that they can fit into the fixed channel spacing of the DFT filter banks in the following stages. Due to the lowered sample rate, these back-end DFT filter banks can have either fixed or variable number of channels. Repeatedly using this multistage architecture, channels with different bandwidths can be isolated. The design and implementation of the proposed channelizer are discussed in detail.published_or_final_versio

Clinicopathological study of renal biopsies after liver transplantation

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Post-growth annealing induced change of conductivity in As-doped ZnO grown by radio frequency magnetron sputtering

Arsenic-doped ZnO films were fabricated by radio frequency magnetron sputtering method at a relatively low substrate temperature of 200 C. Post-growth annealing in air was carried out up to a temperature of 1000 C. The samples were characterized by Hall measurement, positron annihilation spectroscopy (PAS), secondary ion mass spectroscopy (SIMS), and cathodoluminescence (CL). The as-grown sample was of n-type and it converted to p-type material after the 400 C annealing. The resulting hole concentration was found to increase with annealing temperature and reached a maximum of 6 10 17cm -3 at the annealing temperature of 600 C. The origin of the p-type conductivity was consistent with the As Zn(V Zn) 2 shallow acceptor model. Further increasing the annealing temperature would decrease the hole concentration of the samples finally converted the sample back to n-type. With evidence, it was suggested that the removal of the p-type conductivity was due to the dissociation of the As Zn(V Zn) 2 acceptor and the creation of the deep level defect giving rise to the green luminescence. © 2011 American Institute of Physics.published_or_final_versio

Acute gastroenteritis in Hong Kong: A population-based telephone survey

A population-based telephone survey of acute gastroenteritis (AG) was conducted in Hong Kong from August 2006 to July 2007. Study subjects were recruited through random digit-dialling with recruitments evenly distributed weekly over the 1-year period. In total, 3743 completed questionnaires were obtained. An AG episode is defined as diarrhoea 3 times or any vomiting in a 24-h period during the 4 weeks prior to interview, in the absence of known non-infectious causes. The prevalence of AG reporting was 7%. An overall rate of 091 (95% CI 081-101) episodes per person-year was observed with women having a slightly higher rate (094, 95% CI 079-108) than men (088, 95% CI 073-104). The mean duration of illness was 36 days (s.d.=552). Thirty-nine percent consulted a physician, 19% submitted a stool sample for testing, and 26% were admitted to hospital. Of the subjects aged 15 ≥ years, significantly more of those with AG reported eating raw oysters (OR 24, 95% CI 13-44), buffet meals (OR 18, 95% CI 13-25), and partially cooked beef (OR 18, 95% CI 12-27) in the previous 4 weeks compared to the subjects who did not report AG. AG subjects were also more likely to have had hot pot, salad, partially cooked or raw egg or fish, sushi, sashimi, and snacks bought at roadside in the previous 4 weeks. This first population-based study on the disease burden of AG in Asia showed that the prevalence of AG in Hong Kong is comparable to that experienced in the West. The study also revealed some risky eating practices that are more prevalent in those affected with AG. Copyright © 2009 Cambridge University Press.published_or_final_versio

Management of recurrent hepatocellular carcinoma after liver transplant – a single center experience

Background: Hepatocellular carcinoma (HCC) recurs in 10-60% of patients after liver transplantation and carries very dismal prognosis. Optimal management of this condition has yet to be defined. Patients and Methods: All adult patients with HCC within the UCSF (University of California, San Francisco) criteria who underwent liver transplantation at Queen Mary Hospital during the period from July 1995 to September 2013 were reviewed. Two hundred and fifty-two patients were included in the analysis. They were divided into three groups for comparison: with intrahepatic recurrence (IR), with multiple or extrahepatic recurrence (MR), with no recurrence (NR). Results: HCC recurrence occurred in 35 (13.9%) patients, 3 with IR and 32 with MR. Patients in the IR and MR groups had a younger age (51 vs. 51 vs. 56 years; p=0.007), a higher pretransplant serum α-fetoprotein level (27 vs. 97.5 vs. 18 ng/mL; p=0.005), more tumor nodules (4 vs. 2 vs. 1; p=0.003) and a higher incidence of lymphovascular permeation (33% vs. 59% vs. 27%; p=0.001) than patients in the NR group. More patients in the IR and MR groups had tumors beyond the UCSF criteria on histopathology (67% vs. 56% vs. 17%) when compared with the NR group. Treatments for IR included hepatectomy, radiofrequency ablation and transarterial chemoembolization. One patient with IR remained alive 3 years after last treatment. Overall survival in the IR group was longer than that in the MR group (59 vs. 30.4 months; p<0.001). Time from transplant to recurrence was similar between the two groups (23.1 vs. 12 months; p=0.141). Conclusions: Recurrence of HCC after liver transplantation is not uncommon. Aggressive surgical treatment may prolong survival in patients with IR only. Prognosis for patients with MR is dismal. Effective systemic therapy is urgently needed.published_or_final_versio