Results of a Search for Sub-GeV Dark Matter Using 2013 LUX Data.

The scattering of dark matter (DM) particles with sub-GeV masses off nuclei is difficult to detect using liquid xenon-based DM search instruments because the energy transfer during nuclear recoils is smaller than the typical detector threshold. However, the tree-level DM-nucleus scattering diagram can be accompanied by simultaneous emission of a bremsstrahlung photon or a so-called "Migdal" electron. These provide an electron recoil component to the experimental signature at higher energies than the corresponding nuclear recoil. The presence of this signature allows liquid xenon detectors to use both the scintillation and the ionization signals in the analysis where the nuclear recoil signal would not be otherwise visible. We report constraints on spin-independent DM-nucleon scattering for DM particles with masses of 0.4-5 GeV/c^{2} using 1.4×10^{4} kg day of search exposure from the 2013 data from the Large Underground Xenon (LUX) experiment for four different classes of mediators. This analysis extends the reach of liquid xenon-based DM search instruments to lower DM masses than has been achieved previously.

Epidemiology of tuberculosis and HIV coinfections in Singapore, 2000-2014.

Cross-matching of records between Singapore's tuberculosis and HIV registries showed that 3.3% of individuals with tuberculosis (TB) were coinfected with HIV (2000-2014), the TB incidence among individuals with HIV infection was 1.65 per 100 person-years, and 53% of coinfections were diagnosed within 1 month of each other. The findings supported joint prevention programmes for early diagnosis and treatment.

Results from a Search for Dark Matter in the Complete LUX Exposure.

We report constraints on spin-independent weakly interacting massive particle (WIMP)-nucleon scattering using a 3.35×10^{4} kg day exposure of the Large Underground Xenon (LUX) experiment. A dual-phase xenon time projection chamber with 250 kg of active mass is operated at the Sanford Underground Research Facility under Lead, South Dakota (USA). With roughly fourfold improvement in sensitivity for high WIMP masses relative to our previous results, this search yields no evidence of WIMP nuclear recoils. At a WIMP mass of 50 GeV c^{-2}, WIMP-nucleon spin-independent cross sections above 2.2×10^{-46} cm^{2} are excluded at the 90% confidence level. When combined with the previously reported LUX exposure, this exclusion strengthens to 1.1×10^{-46} cm^{2} at 50 GeV c^{-2}.

First Searches for Axions and Axionlike Particles with the LUX Experiment.

The first searches for axions and axionlike particles with the Large Underground Xenon experiment are presented. Under the assumption of an axioelectric interaction in xenon, the coupling constant between axions and electrons g_{Ae} is tested using data collected in 2013 with an exposure totaling 95 live days ×118 kg. A double-sided, profile likelihood ratio statistic test excludes g_{Ae} larger than 3.5×10^{-12} (90% C.L.) for solar axions. Assuming the Dine-Fischler-Srednicki-Zhitnitsky theoretical description, the upper limit in coupling corresponds to an upper limit on axion mass of 0.12 eV/c^{2}, while for the Kim-Shifman-Vainshtein-Zhakharov description masses above 36.6 eV/c^{2} are excluded. For galactic axionlike particles, values of g_{Ae} larger than 4.2×10^{-13} are excluded for particle masses in the range 1-16 keV/c^{2}. These are the most stringent constraints to date for these interactions.

Limits on Spin-Dependent WIMP-Nucleon Cross Section Obtained from the Complete LUX Exposure.

We present experimental constraints on the spin-dependent WIMP-nucleon elastic cross sections from the total 129.5 kg yr exposure acquired by the Large Underground Xenon experiment (LUX), operating at the Sanford Underground Research Facility in Lead, South Dakota (USA). A profile likelihood ratio analysis allows 90% C.L. upper limits to be set on the WIMP-neutron (WIMP-proton) cross section of σ_{n}=1.6×10^{-41} cm^{2} (σ_{p}=5×10^{-40} cm^{2}) at 35 GeV c^{-2}, almost a sixfold improvement over the previous LUX spin-dependent results. The spin-dependent WIMP-neutron limit is the most sensitive constraint to date.

Factors associated with influenza vaccine uptake in older adults living in the community in Singapore.

In Singapore, influenza vaccination is recommended for persons at higher risk of complications of seasonal influenza, including those with chronic medical conditions and the elderly (individuals aged ⩾65 years). We investigated the factors associated with influenza vaccine uptake based on a nationally representative sample of community-dwelling adults aged >50 years. The data for this study were obtained from the National Health Surveillance Survey (NHSS) 2013. The association between influenza vaccine uptake and socio-demographic and health-related variables was analysed using univariable and multivariable logistic regression models. Of 3700 respondents aged ⩾50 years in the NHSS, 15·2% had received seasonal influenza vaccination in the past year. Older age, single marital status and economic inactivity were the socio-demographic variables independently associated with vaccine uptake. Health-related factors which were predictive of influenza vaccine uptake were sufficient total physical activity, better self-rated health, having at least one medical condition at risk of influenza complications and a regular family doctor/general practitioner. Influenza vaccine uptake in community-dwelling older adults was low. Our findings are of relevance in the formulation of public health policies and targeted health promotion strategies to increase vaccine uptake in this population group.

A large common-source outbreak of norovirus gastroenteritis in a hotel in Singapore, 2012.

An outbreak of gastroenteritis affected 453 attendees (attack rate 28·5%) of six separate events held at a hotel in Singapore. Active case detection, case-control studies, hygiene inspections and microbial analysis of food, environmental and stool samples were conducted to determine the aetiology of the outbreak and the modes of transmission. The only commonality was the food, crockery and cutlery provided and/or handled by the hotel's Chinese banquet kitchen. Stool specimens from 34 cases and 15 food handlers were positive for norovirus genogroup II. The putative index case was one of eight norovirus-positive food handlers who had worked while they were symptomatic. Several food samples and remnants tested positive for Escherichia coli or high faecal coliforms, aerobic plate counts and/or total coliforms, indicating poor food hygiene. This large common-source outbreak of norovirus gastroenteritis was caused by the consumption of contaminated food and/or contact with contaminated crockery or cutlery provided or handled by the hotel's Chinese banquet kitchen.

Improved Limits on Scattering of Weakly Interacting Massive Particles from Reanalysis of 2013 LUX Data.

We present constraints on weakly interacting massive particles (WIMP)-nucleus scattering from the 2013 data of the Large Underground Xenon dark matter experiment, including 1.4×10^{4} kg day of search exposure. This new analysis incorporates several advances: single-photon calibration at the scintillation wavelength, improved event-reconstruction algorithms, a revised background model including events originating on the detector walls in an enlarged fiducial volume, and new calibrations from decays of an injected tritium ß source and from kinematically constrained nuclear recoils down to 1.1 keV. Sensitivity, especially to low-mass WIMPs, is enhanced compared to our previous results which modeled the signal only above a 3 keV minimum energy. Under standard dark matter halo assumptions and in the mass range above 4 GeV c^{-2}, these new results give the most stringent direct limits on the spin-independent WIMP-nucleon cross section. The 90% C.L. upper limit has a minimum of 0.6 zb at 33 GeV c^{-2} WIMP mass.

Results on the Spin-Dependent Scattering of Weakly Interacting Massive Particles on Nucleons from the Run 3 Data of the LUX Experiment.

We present experimental constraints on the spin-dependent WIMP (weakly interacting massive particle)-nucleon elastic cross sections from LUX data acquired in 2013. LUX is a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota), which is designed to observe the recoil signature of galactic WIMPs scattering from xenon nuclei. A profile likelihood ratio analysis of 1.4×10^{4} kg day of fiducial exposure allows 90% C.L. upper limits to be set on the WIMP-neutron (WIMP-proton) cross section of σ_{n}=9.4×10^{-41} cm^{2} (σ_{p}=2.9×10^{-39} cm^{2}) at 33 GeV/c^{2}. The spin-dependent WIMP-neutron limit is the most sensitive constraint to date.

Seroepidemiology of dengue virus infection in the adult population in tropical Singapore.

To assess the impact of past dengue epidemics in Singapore, we undertook a national seroepidemiological study to determine the prevalence of past dengue virus (DENV) infection in the adult population in 2010 and make comparisons with the seroprevalence in 2004. The study involved residual sera from 3293 adults aged 18-79 years who participated in a national health survey in 2010. The overall prevalence of anti-DENV IgG antibodies was 56·8% (95% confidence interval 55·1-58·5) in 2010. The seroprevalence increased significantly with age. Males had significantly higher seroprevalence than females (61·5% vs. 53·2%). Among the three major ethnic groups, Malays had the lowest seroprevalence (50·2%) compared to Chinese (57·0%) and Indians (62·0%). The age-standardized seroprevalence in adults was significantly lower in 2010 (54·4%) compared to 2004 (63·1%). Older age, male gender, Indian ethnicity, permanent residency and being home-bound were independent risk factors significantly associated with seropositivity. About 43% of the Singapore adult resident population remain susceptible to DENV infection as a result of the successful implementation of a comprehensive nationwide Aedes surveillance and control programme since the 1970s. Vector suppression and concerted efforts of all stakeholders in the community remain the key strategy in the prevention and control of dengue.

Prevalence of antibodies against measles, mumps and rubella in the childhood population in Singapore, 2008-2010.

We undertook a national paediatric seroprevalence survey of measles, mumps and rubella (MMR) in Singapore to assess the impact of the national childhood immunization programme against these three diseases after introduction of the trivalent MMR vaccine in 1990. The survey involved 1200 residual sera of Singapore residents aged 1-17 years collected from two hospitals between 2008 and 2010. The overall prevalence of antibodies against measles, mumps and rubella was 83∙1% [95% confidence interval (CI) 80∙9-85∙1], 71.8% (95% CI 69∙1-74∙2) and 88∙5% (95% CI 86∙6-90∙2), respectively. For all three diseases, the lowest prevalence was in children aged 1 year (47∙8-62∙3%). The seroprevalence of the vaccinated children declined over time. The national MMR immunization programme is effective in raising the herd immunity of the childhood population, although certain age groups are more susceptible to infection, in particular, those who are not eligible for vaccination at age <15 months.

Correlations between clinical illness, respiratory virus infections and climate factors in a tropical paediatric population.

Weekly (August 2003-December 2008) numbers of five common paediatric diseases and the incidence of respiratory viruses were obtained from a children's hospital in Singapore and correlated with climate data using multivariate time-series techniques. Upper respiratory tract infections were positively correlated with the incidences of influenza A, B, respiratory syncytial virus (RSV) and parainfluenza viruses (types 1-3 combined). Lower respiratory tract infections were positively correlated with only the incidence of RSV. Both upper and lower respiratory tract infections were negatively correlated with relative humidity. Asthma admissions were negatively correlated with maximum temperature and positively correlated with the incidence of influenza B and increasing hours of sunshine. Although sporadic cases of adenovirus infection were identified, not enough cases were available for a more detailed analysis. Gastroenteritis and urinary tract infections, included as control diseases, were not correlated significantly with any climate parameters. These correlations are compatible with current understanding of respiratory virus survival under certain climate conditions and may assist the prediction of disease burdens and hospital resource planning in such tropical environments.

Mortality among tuberculosis patients on treatment in Singapore.

OBJECTIVE: To identify the risk factors associated with mortality among tuberculosis (TB) patients on treatment in Singapore. DESIGN: A retrospective cohort study of 7433 TB patients notified and started on TB treatment from 2000 to 2006 was conducted. Cox regression analysis was used to determine independent risk factors for mortality. RESULTS: Of 7433 patients who started TB treatment between 2000 and 2006, there were 884 deaths (11.9%) from any cause. Older age, male sex, being in a long-term care facility, having comorbidity, absence of cough, more than one site of TB, bacteriologically confirmed laboratory results, resistance to at least isoniazid (INH) and rifampicin (RMP) and absence of cavity were strongly associated with all-cause mortality among TB patients. A total of 203 patients (2.7%) died of TB. Risk factors for death due to TB were older age, male sex, Malay ethnicity, being in a long-term care facility, absence of cough, more than one site of TB, bacteriologically confirmed laboratory results and resistance to at least INH and RMP or to at least INH but not RMP. CONCLUSION: It is important to identify TB patients with risk factors related to mortality so that appropriate and timely interventions can be instituted to prevent deaths among TB patients.

Inoculation injuries: inter-professional differences in risk-taking and reporting.

Guidelines and protocols have been introduced to minimize the risk of transmission of blood-borne viral infections during surgical procedures. However, adherence to these guidelines is reported to be less than complete. A survey of operating theatre professionals was undertaken in one NHS Trust to explore the incidence of inoculation injuries and the extent of non-reporting, together with underlying reasons. A response rate of 72.5% (200/276) was achieved. Significantly more surgeons than nurses and midwives had sustained inoculation injuries: 79/90 (87.8%) compared with 66/106 (62.3%; P<0.001). However, surgeons were significantly less likely than other professionals to report their injuries 39/74 (52.7%) compared with 59/65 (90.8%; P<0.001). It would appear that surgeons' disregard for published guidelines is placing them at a greater risk of contracting blood-borne viral infections than other professionals.

A preliminary investigation into bacterial contamination of Welsh emergency ambulances.

OBJECTIVES: The objective of this regional study across Wales was to perform a preliminary examination of Welsh emergency vehicles to determine levels of bacterial contamination. METHODS: Specific sites within emergency vehicles were swabbed, before and after vehicle cleaning, over a 12 month period, on a monthly basis. All swabs were sent to pathology laboratories for culturing and analysis. RESULTS: Results showed that most sites within emergency vehicles across Wales were contaminated with a range of bacterial species before vehicle cleaning. After vehicle cleaning, many sites in vehicles were still contaminated, and some sites that were previously uncontaminated, became freshly contaminated as a result of cleaning methods used. CONCLUSIONS: The authors conclude that the Welsh emergency vehicles examined exhibited an unacceptable level of bacterial contamination. This finding should be carefully considered and all attempts must be made to tackle the problem of vehicle cleanliness and infection control.

Diabetes mortality in Singapore, 1991--a preliminary study.

OBJECTIVES: The study was undertaken to estimate the contribution of diabetes mellitus to total mortality in Singapore and to study the mortality experience among known diabetics in Singapore by sex, age-group and ethnic group. METHODS: Death certificates of all persons who died in Singapore between 1 January 1991 and 31 August 1991 (n = 9,197) were reviewed. Records which mentioned diabetes mellitus as an underlying or contributory cause of death were selected as being a diabetic case (n = 1,010). RESULTS: If all diabetes related deaths were considered, diabetes mellitus would account for 9.3% of all deaths in Singapore in 1991, i.e. four times higher than the figure of 2.3% in the official statistics. Ischaemic heart disease was the leading cause of death in all age-groups. Renal failure was a major cause of death before the age of 55 while cerebrovascular disease and respiratory tract infections were important causes of death after the age of 64. Renal failure was the leading cause of death among Chinese diabetics below the age of 65. Ischaemic heart disease was the main cause of death among Indian and Malay diabetics. As compared to the general population, Chinese diabetics were more likely to die from renal failure while Indian and Malay diabetics were more likely to die from ischaemic heart disease.

Gender differences in outcome after an acute myocardial infarction in Singapore.

OBJECTIVES: To characterise gender and age-related differences in presentation and outcome after an acute myocardial infarction (AMI). DESIGN: Data were derived retrospectively from the Singapore Myocardial Infarction Registry from 1988 through 1997. This database comprised all AMI cases for ages between 20 and 64 years (group A). For approximately three months a year, data were also collected for all AMI cases above the age of 64 years (group B). There were 13,048 and 4,425 cases in groups A and B respectively. RESULTS: In age - standardised AMI rates, males outnumbered females by a factor of 4.0 and 1.7 for groups A and B respectively.The median age of presentation was higher in females for both age groups being 58 years versus 54 years for group A and 75 years versus 72 years for group B. Younger females had worse survival at 28 days and were more likely to have prior ischaemic heart disease and require resuscitation. They were also more likely to have atypical symptoms. Previous myocardial infarction was not different between the sexes in both groups. Among the older age group, there was no gender difference in prior ischaemic heart disease, 28-day survival and requirement for resuscitation. CONCLUSION: Women who have AMI tend to be older than men. Gender differences are age-specific. Women who are 64 years and below have more atypical symptoms, prior ischaemic heart disease and worse prognosis than men after AMI. These differences are not seen in those over the age of 64.

Recording patient temperature--are we getting it right?

Temperature recordings can provide important patient information in a variety of clinical settings, so it is vital that readings are correct. A survey of current practice, however, revealed disturbing variations from established guidelines.

Surveillance of tuberculosis treatment outcomes of Singapore citizens and permanent residents, 2002-2011.

SETTING: Singapore, which had a tuberculosis (TB) incidence rate of 41 per 100,000 resident population in 2011. OBJECTIVE: To report the outcomes of Singapore citizens and permanent residents treated for TB from 2002 to 2011. METHODS: A computerised treatment surveillance module (TSM) was launched in 2001 to track the progress and outcome of TB patients nationally. Physicians were required to submit an electronic or paper return for every patient at each clinic visit. Treatment adherence, drugs prescribed, treatment delivery mode and final outcome, specified as 'completed treatment', 'lost to follow-up', 'death', 'transferred out', 'permanent cessation of treatment' and 'still on treatment/no final outcome', were captured. Quarterly cohort outcomes at 12-15 months after starting treatment were combined to generate annual treatment outcomes. RESULTS: Treatment completion rates increased from 73.4% to 82.8%. The proportion of patients lost to follow-up decreased from 3.4% to 1.7%, while that of patients still on treatment or with no final outcome decreased from 10.5% to 4.4%. The death rate ranged between 10.2% and 11.7%; the majority were not attributed to TB. CONCLUSION: TB treatment completion among Singapore citizens and permanent residents has improved since 2002 as the likely result of the TSM and other initiatives introduced over the past decade.

Notified tuberculosis among Singapore residents by ethnicity, 2002-2011.

SETTING: The National Tuberculosis Programme in Singapore where, among resident cases, higher tuberculosis (TB) rates have been reported in ethnic Malays. OBJECTIVE: To describe the socio-demographic and clinical characteristics of resident TB cases by ethnicity, and to assess whether Malays differ from other groups in terms of the above parameters. DESIGN: Cross-sectional review of records from the tuberculosis registry's electronic database. RESULTS: Among 15 622 resident cases notified, 72.2% were Chinese, 18.7% Malay, 5.8% Indian and 2.9% were from other minorities. Compared to other ethnicities, Malays were more likely to be incarcerated at the time of notification (odds ratio [OR] 3.70, 95%CI 3.03-4.52) and clustered at the same residential address (OR 1.65, 95%CI 1.44-1.89), but were less likely to be aged ≥65 years (OR 0.61, 95%CI 0.54-0.70) or to reside in high-cost housing (OR 0.11, 95%CI 0.07-0.17). In terms of disease characteristics, more Malays had diabetes mellitus (OR 1.54, 1.37-1.73), a highly-positive acid-fast bacilli smear (OR 1.64, 95%CI 1.47-1.83) and cavitary disease on chest X-ray (OR 1.41, 95%CI 1.28-1.55). CONCLUSION: Compared to other ethnicities, reported TB cases among Malays were more severe and were likely to be more infectious. Increased vigilance in case management and contact investigations, as well as an improvement in the socio-economic conditions of this community, are required to reduce TB rates in this ethnic group.