STEW: Simultaneous Task EEG Workload Data Set.

This paper describes an open access electroencephalography (EEG) data set for multitasking mental workload activity induced by a single-session simultaneous capacity (SIMKAP) experiment with 48 subjects. To validate the database, EEG spectral activity was evaluated with EEGLAB and the significant channels and activities for the experiment are highlighted. Classification performance was evaluated by training a support vector regression model on selected features from neighborhood component analysis based on a nine-point workload rating scale. With a reduced feature dimension, 69% classification accuracy was obtained for 3 identified workload levels from the rating scale with Cohen's kappa of 0.46. Accurate discrimination of mental workload is a desirable outcome in the field of operator performance analysis and BCI development; thus, we hope that our provided database and analyses can contribute to future investigations in this research field.

Design and development of the BD Odon DeviceTM : a human factors evaluation process.

OBJECTIVE: To (1) determine how intended users interact with and use the BD Odon Device in simulation, (2) use these findings to alter progressively the design of the BD Odon Device and (3) validate that these changes have improved the ability of practitioners to use the BD Odon Device. DESIGN: Human factors evaluation study. SETTING: Simulation suite designed to mimic delivery room. POPULATION OR SAMPLE: Three hundred and ninety simulated operative births, performed by 100 practising clinicians. METHODS: Simulated operative vaginal births performed using the BD Odon Device and the device Instructions for use were subjected to three formative human factors evaluations and one human factors validation test. Following each evaluation, findings were reviewed and the design of the BD Odon Device and Instructions for use were modified. MAIN OUTCOME MEASURES: Successful performance of an operative vaginal birth using the BD Odon Device in accordance with provided training and Instructions for use. RESULTS: Using version two of the BD Odon Device, and following exposure to face-to-face training and written instructions, 25% of accouchers were able successfully to perform a simulated operative vaginal birth. In the final evaluation, following device design and training material alterations, all accouchers were able successfully to perform a simulated operative vaginal birth using version four of the BD Odon Device. CONCLUSIONS: Human factors evaluations have enabled a multi-professional device and training materials design team to alter the design of the BD Odon Device and the Instructions for use in an evidence-based fashion. This process has resulted in a device which has a predictable and likely safe pattern of use. TWEETABLE ABSTRACT: Human Factors evaluations help make the BD Odon Device safe and usable for clinical practice.

Dynamical skyrmion state in a spin current nano-oscillator with perpendicular magnetic anisotropy.

We study the spectral characteristics of spin current nano-oscillators based on the Pt/[Co/Ni] magnetic multilayer with perpendicular magnetic anisotropy. By varying the applied magnetic field and current, both localized and propagating spin wave modes of the oscillation are achieved. At small fields, we observe an abrupt onset of the modulation sidebands. We use micromagnetic simulations to identify this state as a dynamical magnetic skyrmion stabilized in the active device region by spin current injection, whose current-induced dynamics is accompanied by the gyrotropic motion of the core due to the skew deflection. Our results demonstrate a practical route for controllable skyrmion manipulation by spin current in magnetic thin films.

Spectral characteristics of the microwave emission by the spin Hall nano-oscillator.

We utilized microwave spectroscopy to study the magnetization oscillations locally induced in a Permalloy film by a pure spin current, which is generated due to the spin Hall effect in an adjacent Pt layer. The oscillation frequency is lower than the ferromagnetic resonance of Permalloy, indicating that the oscillation forms a self-localized nonpropagating spin-wave soliton. At cryogenic temperatures, the spectral characteristics are remarkably similar to the traditional spin-torque nano-oscillators driven by spin-polarized currents. However, the linewidth of the oscillation increases exponentially with temperature and an additional peak appears in the spectrum below the ferromagnetic resonance, suggesting that the spectral characteristics are determined by interplay between two localized dynamical states.

Delayed oseltamivir treatment is associated with longer viral shedding of pandemic (H1N1) 2009 virus.

During the early phase of the influenza pandemic in 2009, all cases of laboratory-confirmed pandemic (H1N1) 2009 (pH1N1) infection required compulsory isolation in hospital. These cases were offered oseltamivir treatment and only allowed to be discharged from the hospital when three consecutive respiratory specimens were negative for the virus by reverse transcription-polymerase chain reaction (RT-PCR). We reviewed the case records of these patients to assess the viral shedding kinetics of the pH1N1 virus. We defined viral shedding duration as the interval from illness onset date to the date of collection of the last positive specimen from the patients. Fifty-six patients were included in the study, of whom 96% received oseltamivir. The median viral shedding duration of pH1N1 virus by viral culture and RT-PCR were 3 days and 4 days, respectively. Patients who started oseltamivir treatment >48 h after onset had a significantly longer median viral shedding duration by viral culture than those who started treatment within 48 h of onset (4 days vs. 2 days, P=0·014).

The effect of APOE genotype on brain levels of oxysterols in young and old human APOE epsilon2, epsilon3 and epsilon4 knock-in mice.

Despite apolipoprotein E's important role in cholesterol transport and metabolism in the brain as well as its influence on Alzheimer's disease, the impact of the human APOE genotype on cholesterol metabolism in brain has not been fully examined. This study was carried out to investigate APOE genotype effects on oxysterols measured. In this study the measurement of cholesterol and several oxysterols in the brains of human APOE epsilon2, epsilon3 and epsilon4 knock-in mice at 8 weeks and 1 year of age using gas chromatography mass spectrometry (GC-MS) demonstrated no APOE genotype or age effect on total brain cholesterol and the oxysterol 24-hydroxycholesterol. The level of 27-hydroxycholesterol was elevated in 1 year old animals for all APOE genotypes. Interestingly, lathosterol an indicator of cholesterol synthesis was significantly reduced in the 1 year old animals for all APOE genotypes. APOE epsilon4 expressing mice exhibited statistically lower levels of lathosterol compared to APOE epsilon2 in both the young and old mice. Oxidized cholesterol metabolites were significantly lower in APOE epsilon2 mice compared to other genotypes at 8 weeks old. Although minimal differences were observed between APOE E3 and E4 knock-in (KI) mice, these findings indicate that there are some clear APOE genotype specific effects on brain cholesterol synthesis and associated metabolic pathways, particularly in APOE epsilon2 KI mice.

Molecular epidemiology demonstrated three emerging clusters of human immunodeficiency virus type 1 subtype B infection in Hong Kong.

We conducted a molecular epidemiological study on newly diagnosed human immunodeficiency virus type 1 (HIV-1)-infected patients in Hong Kong to identify the epidemiological linkage of HIV-1 infection in the locality. Reverse transcription polymerase chain reaction (RT-PCR) for HIV-1 was performed on newly diagnosed HIV-1-positive sera collected from January 2002 to December 2006. PCR products correspond to the env C2V3V4 region and gag p17/p24 junction of the HIV-1 genome were nucleotide sequenced. Phylogenetic analyses performed on the acquired nucleotide sequences revealed that CRF01_AE and subtype B were the two dominant HIV-1 subtypes. Analyses also demonstrated the presence of three emerging HIV-1 clusters among the subtype B sequences in Hong Kong. Individual cluster possesses a unique cluster-specific amino acid signature for identification. Data show that one of the clusters (Cluster I) is rapidly expanding. In addition to the unique cluster-specific amino acid signature, the majority of sequences in Cluster I harbor a 6-amino acid insertion at the gag p17/p24 junction in a region that is thought to be closely associated with HIV-1 infectivity.

Audit of perioperative blood transfusion.

The main goal of perioperative transfusion is to reduce the morbidity and mortality associated with inadequate delivery of oxygen to the tissues during surgery. In this audit, the primary trigger for transfusion was clinical anaemia assessed by examination of a patient's conjunctiva [40.7%] followed by estimation of blood loss of greater 20% of total blood volume [29.3%]. Haemoglobin estimation in the operation theater was not done in 45.9% of studied patients and only 7.8% patients had transfusion based on this criteria. A common practice is to transfuse blood for hypovolaemia. This was the indication for blood transfusion in 96 patients (7.8%). Inappropriate use of blood in this way has led to wastage of a valuable resource and exposed patients to potential risks of unwanted side effects. Analysis of haemoglobin estimation at recovery room showed 32% of patient with co-morbidities had Hb > 10 gm% while 65% and 29.5% of patients without co-morbidities had Hb > 8 gm% and 10 gm% respectively. This reflects the practice of anaesthetists in maintaining a target of Hb of 10 gm% for both groups of patients while a target of 8 gm% is still relatively safe for patients with good cardiovascular reserves. This has resulted in signifant use of homologous blood which will certainly burden the blood bank and increase the cost of healthcare.

Surveillance of acute flaccid paralysis in Hong Kong: 1997 to 2002.

OBJECTIVES: To describe the characteristics of patients reported with acute flaccid paralysis between 1997 and 2002, and to evaluate the performance of the acute flaccid paralysis surveillance system using indicators recommended by the World Health Organization. DESIGN: Retrospective study. SETTING: Department of Health, Hong Kong. PARTICIPANTS: Children aged younger than 15 years who were reported to the Department of Health between 1997 and 2002 with acute flaccid paralysis. RESULTS: Of 120 children with acute flaccid paralysis reported between 1997 and 2002, 42% were younger than 5 years of age. None of the cases were acute poliomyelitis or polio-compatible. A neurological cause was identified in 67.5% of cases, of which the most common was Guillain-Barre syndrome (42%), followed by transverse myelitis (15%). All except one of the performance indicators consistently met World Health Organization requirements and thus demonstrated the effectiveness of the acute flaccid paralysis surveillance programme. The acute flaccid paralysis notification rate consistently exceeded 1.0 per 100 000 population below 15 years of age. The requirement for adequate stool investigation was the single indicator that did not satisfy World Health Organization requirements. This highlighted the importance of maintaining physicians' awareness of acute flaccid paralysis surveillance. CONCLUSION: Hong Kong should remain vigilant for acute flaccid paralysis. The effective surveillance system and its evaluation may serve as a model for surveillance of other infectious diseases.

The lack of epidemiological link between the HIV type 1 infections in Hong Kong and Mainland China.

Blood samples were collected from 139 newly reported HIV-1 infections in Hong Kong over a 3-year period between 1999 and 2001, representing 22.8% of all reported cases. A majority of the patients were male (85.6%), Chinese (74%), and adult (97.1%) and acquired HIV-1 through sexual transmission (88.2%). The B and CRF01_AE were the major subtypes detected--49.6% and 44.6%, respectively. Over time, the frequency of CRF01_AE subtype increased, the B subtype decreased, and new subtypes of C (4) 2.8%, B' (1) 0.7%, and CRF07_BC (3) 2.2% emerged. The CRF01_AE subtype was commoner in female, Chinese, heterosexuals, and injection drug users whereas B subtype was commoner in male, white, and people with homosexual/bisexual contacts. There was no common source of infection from the analysis except a discernible cluster of Vietnamese injection drug users with the CRF01_AE subtype. The molecular findings did not suggest an epidemiological link between HIV infection in Hong Kong and Mainland China. Hong Kong's longstanding and extensive methadone treatment network may have contributed to the phenomenon.

Re-emergence of fatal human influenza A subtype H5N1 disease.

Human disease associated with influenza A subtype H5N1 re-emerged in January, 2003, for the first time since an outbreak in Hong Kong in 1997. Patients with H5N1 disease had unusually high serum concentrations of chemokines (eg, interferon induced protein-10 [IP-10] and monokine induced by interferon gamma [MIG]). Taken together with a previous report that H5N1 influenza viruses induce large amounts of proinflammatory cytokines from macrophage cultures in vitro, our findings suggest that cytokine dysfunction contributes to the pathogenesis of H5N1 disease. Development of vaccines against influenza A (H5N1) virus should be made a priority.

Cavitation phenomena in mechanical heart valves: the role of squeeze flow velocity and contact area on cavitation initiation between two impinging rods.

In this study, the closing dynamics of two impinging rods were experimentally analyzed to simulate the cavitation phenomena associated with mechanical heart valve closure. The purpose of this study was to investigate the cavitation phenomena with respect to squeeze flow between two impinging surfaces and the parameter that influences cavitation inception. High-speed flow imaging was employed to visualize and identify regions of cavitation. The images obtained favored squeeze flow as an important mechanism in cavitation inception. A correlation study of the effects of impact velocities, contact areas and squeeze flow velocity on cavitation inception showed that increasing impact velocities results in an increase in the risk of cavitation. It was also shown that for similar impact velocities, regions near the point of impact were found to cavitate later for those with smaller contact areas. It was found that the decrease in contact areas and squeeze flow velocities would delay the onset and reduce the intensity of cavitation. It is also interesting to note that the squeeze flow velocity alone does not provide an indication if cavitation inception will occur. This is corroborated by the wide range of published critical squeeze flow velocity required for cavitation inception. It should be noted that the temporal acceleration of fluid, often neglected in the literature, can also play an important role on cavitation inception for unsteady flow phenomenon. This is especially true in mechanical heart valves, where for the same leaflet closing velocity, valves with a seat stop were observed to cavitate earlier. Based on these results, important inferences may be made to the design of mechanical heart valves with regards to cavitation inception.

The long-term efficacy of plasma-derived hepatitis B vaccine in babies born to carrier mothers.

The long-term efficacy of a childhood hepatitis B vaccination programme was evaluated. A total of 112 newborn babies of hepatitis B carrier mothers were given hepatitis B immune globulin (HBIG) and a 10-microg three-dose regimen of plasma-derived vaccine administered at a conventional (0, 1, 6 months), delayed (2, 3, 8 months) or accelerated (0, 1, 2 months) schedule. The vaccinees were followed up to determine their anti-HBs status over a 16-year period. Upon completion of the vaccination schedules, 92.6% developed antibody against surface antigen (anti-HBs) seroconverion, the rate of which fell to 33.3% at year 16. The three schedules were equally effective in preventing chronic infection, with a protective efficacy of 88.9% from hepatitis B surface antigen (HBsAg) carriage, compared with historical control. Vaccinees on the delayed schedule had a slightly higher seroconversion rate over years, and were better able to maintain an anti-HBs level of > or = 100 iu/L. Overall, a quarter demonstrated evidence of exposure to the virus, being positive for antibody against core antigen or HBsAg, or mounting a rise in anti-HBs during the follow-up period. We conclude that a three-dose hepatitis B vaccination regimen is generally effective in protecting newborns of hepatitis B carrier mothers from infection and chronic carriage. Booster is not needed even after 16 years of monitoring.

Perioperative death in Malaysia: the transition phase from a developing nation to a developed one.

This paper examines the surgical pathology associated with perioperative deaths in a country that is undergoing the transition from a developing to a developed nation status. The data from an ongoing nation-wide perioperative mortality study was prospectively collected for the period July 1996 to December 1997 and analyzed. The surgical pathology related to perioperative deaths in Malaysia is different from other developing and developed countries. While death from trauma and the late presentation of surgical conditions are similar to developing countries, infective gastrointestinal conditions were rarely encountered. Diseases associated with advanced age such as colorectal cancer, peptic ulcer, urological diseases and vascular conditions are beginning to emerge. As the country races towards a developed nation status, increasing life expectancy and changing life-styles are expected to influence the disease pattern. The planning of surgical facilities and manpower development must recognize the changes taking place.

The implication of a reduced-dose hepatitis B vaccination schedule in low risk newborns.

Five hundred and seventy-four babies born to HBsAg negative mothers in Hong Kong received either a regular (5 micro g) or reduced (2.5 micro g) three-dose regimen of recombinant hepatitis B vaccine. A significantly higher anti-HBs positivity rate (>or=10 mIU/ml), geometric mean titer (GMT) and the maintenance of a high anti-HBs level (>or=100 mIU/ml) were observed with the regular-dose regimen. The differences persisted, however, only up to 1 year post-vaccination. Over an 8-year period, only 1% of the vaccinees demonstrated anti-HBc seroconversion and none had become HBsAg positive. The long-term efficacy of the reduced-dose regimen was confirmed, even in an HBV endemic population.

Pulsatile flow studies of a porcine bioprosthetic aortic valve in vitro: PIV measurements and shear-induced blood damage.

A two-dimensional particle image tracking velocimetry (PIV) system has been used to map the velocity vector fields and Reynolds stresses in the immediate downstream vicinity of a porcine bioprosthetic heart valve at the aortic root region in vitro under pulsatile flow conditions. Measurements were performed at five different time steps of the systolic phase of the cardiac cycle. The velocity vector fields and Reynolds stress mappings at different time steps allowed us to chart a time history of the stress levels experienced by fluid particles as they move across the aortic root. This Lagrangian description of the stresses experienced by individual blood cells enabled us to estimate the propensity of shear-induced damage to platelets and red blood cells. Coupled with flow visualization techniques, the hydrodynamic consequences of introducing a porcine bioprosthetic heart valve into the aortic root was examined. Although the PIV measurements may lack the accuracy of single point measuring systems, the overall view of the flow in the aortic root region compensates for the shortcoming.

Hepatitis B surface antigen variants in vaccinees, blood donors and an interferon-treated patient.

Variants of hepatitis B virus (HBV), with amino acid substitutions in the major antigenic "a" determinant of hepatitis B surface antigen (HBsAg), have been described mainly in vaccinated children. In the present study in addition to vaccinated children, we have investigated Chinese blood donors positive for anti-HBc alone, and a patient with continuing liver disease after interferon-induced seroconversion to anti-HBs. Variants were detected in two of four children with break-through infections. One child had a double mutation (P142S and G145R) and the other a G145A substitution. Three of seven anti-HBc positive Chinese blood donors had a T131I substitution, whilst the interferon-treated patient had a treble amino acid substitution (P142S, G145R and N146D). The present results indicate that HBsAg variants may exist in individuals other than vaccinated children.

Epidemiology and detection of human immunodeficiency virus among pregnant women in Hong Kong.

OBJECTIVES: To determine the epidemiology of human immunodeficiency virus infection among pregnant women and the neonatal outcomes in Hong Kong. DESIGN: Retrospective observational study composed of two parts: record review of pregnant women and unlinked anonymous screening of cord blood from neonates. SETTING: Two human immunodeficiency virus clinics and the Government Virus Unit. PARTICIPANTS: Female patients attending the two clinics who became pregnant and neonates who underwent routine metabolic screening by the Government Virus Unit between 1992 and 1999. MAIN OUTCOME MEASURES: The outcomes of neonates born to women who had human immunodeficiency virus infection during pregnancy. RESULTS: Forty-one human immunodeficiency virus-related pregnancies were recorded among 32 infected women. Fifteen pregnancies were terminated, of which 14 were in women who knew their infection status before conception. Twenty-six pregnancies continued to term, resulting in 26 live births. Twelve babies were born to women who knew their infection status before delivery. One baby was confirmed to be infected. Six women were given zidovudine for prophylaxis against vertical transmission and none of the babies were infected at birth. Of the remaining 14 human immunodeficiency virus-related pregnancies, the mothers' status became known only at a later date and nine (64.3%) babies were confirmed to be infected at the age of 18 months or older. The rate ratio of giving birth to an infected baby was 8.18 from mothers who did not know their status antenatally. Unlinked anonymous screening showed that the seroprevalence rate for human immunodeficiency virus in pregnant women was 0.032% (1/3125) in Hong Kong in 1999. CONCLUSIONS: Human immunodeficiency virus-related pregnancy is not rare in Hong Kong and the majority of infected mothers were not identified and treated. Detection of these pregnancies will be invaluable for the prevention of mother-to-child transmission. Universal antenatal screening of human immunodeficiency virus antibody is proposed as an effective strategy.

A case-controlled study on the use of HBsAg-positive donors for allogeneic hematopoietic cell transplantation.

To compare the clinical and serological outcomes of patients receiving donors' marrow positive or negative for hepatitis B surface antigen (HBsAg), we studied 18 patients of allogeneic hematopoietic cell transplantation receiving HBsAg-positive marrow (group 1) and 18 receiving HBsAg-negative marrow (group 2). The recipients of the 2 groups were matched for hepatitis B virus (HBV) serology, sex, age, underlying hematological diseases, conditioning regimen, and prophylaxis against graft-versus-host diseases. Eight (44.4%) recipients in group 1 and 2 (11.1%) in group 2 suffered from HBV-related hepatitis posttransplant (P =.03). Furthermore, HBV-related hepatic failure was seen in 6 group 1 patients, but in none of the group 2 patients (P =.007). Five of the 9 (55.5%) HBsAg-negative recipients in group 1 became positive after receiving HBsAg-positive marrow. Serum HBV DNA was positive in all 5 donors of these patients, but in none of the donors of recipients who remained HBsAg negative (P =.008). Group 1 patients developing HBV-related hepatitis posttransplant were more likely to have a donor carrying a precore A(1896 )and/or core promoter T(1762)/A(1764) HBV variant (62. 5% versus 0%, P =.007). This study has demonstrated that a high incidence of HBV-related hepatitis was associated with the use of HBsAg-positive marrow for transplant, and a high viral load in the donor appeared to predispose recipients to the development of HBV-related hepatitis posttransplant. Further clinical trials will be necessary to determine the optimal management approach to this problem, including the use of the antiviral agents in the donors and the recipients. (Blood. 2000;96:452-458)