Space Trumps Time When Talking About Objects.

The nature of the relationship between the concepts of space and time in the human mind is much debated. Some claim that space is primary and that it structures time (cf. Lakoff & Johnson, 1980) while others (cf. Walsh, 2003) maintain no difference in status between them. Using fully immersive virtual reality (VR), we examined the influence of object distance and time of appearance on choice of demonstratives (this and that) to refer to objects. Critically, demonstratives can be used spatially (this/that red triangle) and temporally (this/that month). Experiment 1 showed a pattern of demonstrative usage in VR that is consistent with results found in real-world studies. Experiments 2, 3, and 4 manipulated both when and where objects appeared, providing scenarios where participants were free to use demonstratives in either a temporal or spatial sense. Although we find evidence for time of presentation affecting object mention, the experiments found that demonstrative choice was affected only by distance. These results support the view that spatial uses of demonstratives are privileged over temporal uses.

The influence of personal BMI on body size estimations and sensitivity to body size change in anorexia spectrum disorders.

In this cross-sectional study, we investigated the influence of personal BMI on body size estimation in 42 women who have symptoms of anorexia (referred to henceforth as anorexia spectrum disorders, ANSD), and 100 healthy controls. Low BMI control participants over-estimate their size and high BMI controls under-estimate, a pattern which is predicted by a perceptual phenomenon called contraction bias. In addition, control participants' sensitivity to size change declines as their BMI increases as predicted by Weber's law. The responses of women with ANSD are very different. Low BMI participants who have ANSD are extremely accurate at estimating body size and are very sensitive to changes in body size in this BMI range. However, as BMI rises in the ANSD participant group, there is a rapid increase in over-estimation concurrent with a rapid decline in sensitivity to size change. We discuss the results in the context of signal detection theory.

Negative BOLD response in the hippocampus during short-term spatial memory retrieval.

A parieto-medial temporal pathway is thought to underlie spatial navigation in humans. fMRI was used to assess the role of this pathway, including the hippocampus, in the cognitive processes likely to underlie navigation based on environmental cues. Participants completed a short-term spatial memory task in virtual space, which required no navigation but involved the recognition of a target location from a foil location based on environmental landmarks. The results showed that spatial memory retrieval based on environmental landmarks was indeed associated with increased signal in regions of the parieto-medial temporal pathway, including the superior parietal cortex, the retrosplenial cortex, and the lingual gyrus. However, the hippocampus demonstrated a signal decrease below the fixation baseline during landmark-based retrieval, whereas there was no signal change from baseline during retrieval based on viewer position. In a discussion of the origins of such negative BOLD response in the hippocampus, we consider both a suppression of default activity and an increase in activity without a corresponding boost in CBF as possible mechanisms.

A Lean Six Sigma approach to the improvement of the selenium analysis method.

Reliable results represent the pinnacle assessment of quality of an analytical laboratory, and therefore variability is considered to be a critical quality problem associated with the selenium analysis method executed at Western Cape Provincial Veterinary Laboratory (WCPVL). The elimination and control of variability is undoubtedly of significant importance because of the narrow margin of safety between toxic and deficient doses of the trace element for good animal health. A quality methodology known as Lean Six Sigma was believed to present the most feasible solution for overcoming the adverse effect of variation, through steps towards analytical process improvement. Lean Six Sigma represents a form of scientific method type, which is empirical, inductive and deductive, and systematic, which relies on data, and is fact-based. The Lean Six Sigma methodology comprises five macro-phases, namely Define, Measure, Analyse, Improve and Control (DMAIC). Both qualitative and quantitative laboratory data were collected in terms of these phases. Qualitative data were collected by using quality-tools, namely an Ishikawa diagram, a Pareto chart, Kaizen analysis and a Failure Mode Effect analysis tool. Quantitative laboratory data, based on the analytical chemistry test method, were collected through a controlled experiment. The controlled experiment entailed 13 replicated runs of the selenium test method, whereby 11 samples were repetitively analysed, whilst Certified Reference Material (CRM) was also included in 6 of the runs. Laboratory results obtained from the controlled experiment was analysed by using statistical methods, commonly associated with quality validation of chemistry procedures. Analysis of both sets of data yielded an improved selenium analysis method, believed to provide greater reliability of results, in addition to a greatly reduced cycle time and superior control features. Lean Six Sigma may therefore be regarded as a valuable tool in any laboratory, and represents both a management discipline, and a standardised approach to problem solving and process optimisation.

The effect of HIV infection on time off work in a large cohort of gold miners with known dates of seroconversion.

OBJECTIVES: To estimate the effect of HIV infection on time off work. To provide baseline estimates for economic and actuarial models, and for evaluations of ART and other workplace interventions. METHODS: A retrospective cohort study of gold miners with known dates of seroconversion to HIV, and an HIV-negative comparison group, used routinely collected data to estimate the proportion of time off work by calendar period (1992-2002, prior to the introduction of ART), age, time since seroconversion and period before death. The authors calculated ORs for overall time off work and RR ratios (RRR, using multinomial logistic regression) for reasons off work relative to being at work. RESULTS: 1703 HIV-positive and 4859 HIV-negative men were followed for 34 424 person-years. HIV-positive miners spent a higher proportion of time off work than negative miners (20.7% vs 16.1%) due to greater medical and unauthorised absence. Compared with HIV-negative miners, overall time off work increased in the first 2years after seroconversion (adjusted OR 1.40 (95% CI 1.36 to 1.45)) and then remained broadly stable for a number years, reaching 38.8% in the final year before death (adjusted OR 3.27, 95% CI 2.95 to 3.63). Absence for medical reasons showed the strongest link to HIV infection, increasing from an adjusted RRR of 2.66 (95% CI 2.45 to 2.90) for the first 2years since seroconversion to 13.6 (95% CI 11.8 to 15.6) in the year prior to death. CONCLUSIONS: Time off work provides a quantifiable measure of the effect of HIV on overall morbidity. HIV/AIDS affects both labour supply (increased time off work) and demand for health services (increased medical absence). The effects occur soon after seroconversion and stabilise before reaching very high levels in the period prior to death. Occupational health services are an important setting to identify HIV-infected men early.

Efficacy and safety of nemonoxacin versus levofloxacin for community-acquired pneumonia.

Nemonoxacin, a novel nonfluorinated quinolone, exhibits potent in vitro and in vivo activities against community-acquired pneumonia (CAP) pathogens, including multidrug-resistant Streptococcus pneumoniae. Patients with mild to moderate CAP (n = 265) were randomized to receive oral nemonoxacin (750 mg or 500 mg) or levofloxacin (500 mg) once daily for 7 days. Clinical responses were determined at the test-of-cure visit in intent-to-treat (ITT), clinical per protocol (PPc), evaluable-ITT, and evaluable-PPc populations. The clinical cure rates for 750 mg nemonoxacin, 500 mg nemonoxacin, and levofloxacin were 89.9%, 87.0%, and 91.1%, respectively, in the evaluable-ITT population; 91.7%, 87.7%, and 90.3%, respectively, in the evaluable-PPc population; 82.6%, 75.3%, and 80.0%, respectively, in the ITT population; and 83.5%, 78.0%, and 82.3%, respectively, in the PPc population. Noninferiority to levofloxacin was demonstrated in both the 750-mg and 500-mg nemonoxacin groups for the evaluable-ITT and evaluable-PPc populations, and also in the 750 mg nemonoxacin group for the ITT and PPc populations. Overall bacteriological success rates were high for all treatment groups in the evaluable-bacteriological ITT population (90.2% in the 750 mg nemonoxacin group, 84.8% in the 500 mg nemonoxacin group, and 92.0% in the levofloxacin group). All three treatments were well tolerated, and no drug-related serious adverse events were observed. Overall, oral nemonoxacin (both 750 mg and 500 mg) administered for 7 days resulted in high clinical and bacteriological success rates in CAP patients. Further, good tolerability and excellent activity against common causative pathogens were demonstrated. Nemonoxacin (750 mg and 500 mg) once daily is as effective and safe as levofloxacin (500 mg) once daily for the treatment of CAP.

High rates of recurrence in HIV-infected and HIV-uninfected patients with tuberculosis.

BACKGROUND: The rate of recurrent tuberculosis disease due to reinfection, compared with the incidence of new tuberculosis, in those with and without HIV infection is not known. METHODS: In a retrospective cohort study of South African gold miners, men with known dates of seroconversion to HIV (from 1991 to 1997) and HIV-negative men were followed up to 2004. Rates of tuberculosis recurrence >2 years after the first episode were used as a proxy for reinfection disease rates. RESULTS: Among 342 HIV-positive and 321 HIV-negative men who had had 1 previous episode of tuberculosis, rates of recurrence were 19.7 cases per 100 person-years at risk (PYAR; 95% confidence interval [CI], 16.4-23.7) and 7.7 cases per 100 PYAR (95% CI, 6.1-9.8), respectively. The recurrence rate did not vary by duration of HIV infection. Recurrent pulmonary tuberculosis rates >2 years after the first episode were 24.4 cases per 100 PYAR (95% CI, 17.2-34.8) in HIV-positive men and 4.3 cases per 100 PYAR (95% CI, 2.2-8.3) in HIV-negative men, compared with incidence rates of new pulmonary tuberculosis of 3.7 cases per 100 PYAR (95% CI, 3.3-4.1) in HIV-positive men and 0.75 cases per 100 PYAR (95% CI, 0.67-0.84) in HIV-negative men in the same cohort. CONCLUSIONS: Tuberculosis recurrence rates, likely due to reinfection, were much higher than incidence rates. The findings suggest heterogeneity in susceptibility, implying that a vaccine could still provide useful protection in the population and strengthening the case for secondary preventive therapy.

Effects of duration of HIV infection and secondary tuberculosis transmission on tuberculosis incidence in the South African gold mines.

BACKGROUND: HIV increases the risk of tuberculosis directly, through immunosuppression, and indirectly, through onward transmission of Mycobacterium tuberculosis from the increased caseload. We assess the contribution of these two mechanisms by time since seroconversion to HIV. METHODS: The incidence of new pulmonary tuberculosis was estimated in a retrospective cohort study of South African gold miners over 14 years. HIV tests were done in random surveys in 1992-1993, and in clinics. One thousand nine hundred fifty HIV positive men with seroconversion intervals of less than 3 years were identified and linked to medical, demographic and occupational records. They were compared with men who were HIV-negative in a survey, with no later evidence of HIV. Analyses were censored when men were diagnosed with tuberculosis, died or left the mine. RESULTS: Tuberculosis incidence rose soon after HIV infection, reaching 1.4/100 person-years (95% confidence interval 1.1-1.9) within 2 years, and 10.0/100 person-years (95% confidence interval 6.5-15.5) at 10 or more years. By 11 years from seroconversion, nearly half the men had had tuberculosis. Among 5702 HIV-negative men, tuberculosis incidence was 0.48/100 person-years (95% confidence interval 0.33-0.70) in 1991-1993 and doubled over the period of the study (after adjusting for age). Age-adjusted model estimates suggest that half the increase in tuberculosis incidence by time since HIV infection was attributable to increasing incidence over calendar period--the indirect effect. CONCLUSION: For the first time, we have shown that the increase in tuberculosis risk by time since seroconversion reflects both direct effects of HIV increasing susceptibility, and indirect effects due to onward transmission. Innovative and sustained public health measures are needed to reduce Mycobacterium tuberculosis transmission.

Survival from HIV-1 seroconversion in Southern Africa: a retrospective cohort study in nearly 2000 gold-miners over 10 years of follow-up.

OBJECTIVE: To obtain robust estimates of survival with HIV in individuals with known dates of seroconversion in Africa in the pre-antiretroviral era. DESIGN AND METHODS: Mortality rates were estimated in men from four South African gold mines in a retrospective cohort study with 10-year follow-up. HIV testing was carried out with counselling and consent, in random surveys in the early 1990s and in clinics. A total of 1950 HIV-positive men with seroconversion intervals < 3 years were compared with 6164 HIV-negative men with no subsequent evidence of HIV. Unique industry numbers were used to link medical records to demographic and occupational information. Follow-up after leaving the mine was conducted through employment offices across southern Africa, and using South African death registration data. RESULTS: Follow-up was complete for 85% of those who seroconverted. Median survival was 10.5 years overall: 11.5 years for those aged 15-24 at seroconversion, 10.5 years for those aged 25-34, 9.5 years for those aged 35-44, and 6.3 years for those aged 45+ years. The relative mortality rate in comparison with HIV-uninfected miners increased quickly, reaching 13 for those HIV-infected for at least 9 years, and did not vary by age group. Excess mortality increased with age and duration of infection to > 10% per year. Adjusted to age 25-29 years at seroconversion, 5-year survival was 89% and 10-year 62%. DISCUSSION: This study reports by far the largest cohort of individuals with known dates of seroconversion available in Africa. After adjusting for age, the survival pattern was similar to that seen in the West before antiretroviral therapy was available.

Cause of death and presence of respiratory disease at autopsy in an HIV-1 seroconversion cohort of southern African gold miners.

OBJECTIVES: To describe causes of death and respiratory infections in HIV-infected miners in the pre-antiretroviral era, by duration of HIV infection. DESIGN: A retrospective cohort of 1950 gold miners with known dates of HIV seroconversion and 6164 HIV-negative miners was followed from the early 1990s to 2002. METHODS: Causes of death were available from multiple sources: personnel records, clinical records, death certificates and autopsies of cardiorespiratory organs performed for compensation purposes. RESULTS: Causes of death were known for 279 of 308 HIV-positive (91%) and 234 of 254 HIV-negative (92%) men who died while employed or within 6 months of leaving employment. The mortality rate from unnatural causes was similar in HIV-positive and HIV-negative miners and by duration of HIV infection. Among deaths from natural causes, 87% in HIV-positive and 41% in HIV-negative individuals were caused by infection (P < 0.001); 47% of HIV-positive and 26% of HIV-negative individuals had tuberculosis. The proportion of deaths from natural causes with any infection, or with specific infections (tuberculosis, cryptococcus, pneumocystis), did not vary with the duration of HIV infection. Autopsies were performed on 29% of men who died from natural causes: 83% of HIV-positive and 37% of HIV-negative men had respiratory infections (P < 0.001), half of which were clinically undiagnosed. CONCLUSION: Tuberculosis was the leading cause of death in HIV-positive and negative men who died from natural causes. Although the mortality rate from natural causes increased greatly with the duration of HIV infection, the pattern of disease hardly changed, suggesting that slow and fast progressors succumb to the same range of diseases.

Effect of HIV on work-related injury rates in South African gold miners.

OBJECTIVE: Work-related injuries have severe, well-documented economic and social impacts, and injury is a leading cause of death in working adults. As adults of working age are one of the groups most affected by the HIV epidemic, the interaction between work-related injuries and HIV is important. The objective was to calculate the effect of HIV on the rate and severity of work-related injuries by duration of infection. DESIGN AND METHODS: A large, retrospective seroincident cohort of South African gold miners was studied. Data routinely collected by the mines, and assurance company injury data were analysed. HIV-positive and negative miners were compared, allowing the calculation of injury rates and rate ratios. Severity of injuries was measured by the number of days away from work, percentage of permanent disability, and fatalities. RESULTS: Results were available for 1661 HIV-positive and 6166 HIV-negative miners over 10 years. HIV infection increased the rate of work-related injuries overall (adjusted rate ratio, 1.3; 95% confidence interval, 1.1-1.4), but had less effect on severe injuries. Injury rates in HIV-positive men prior to the first positive test were similar to those in HIV-negative men. The injury rate rose soon after the first HIV positive test. After seroconversion there was only weak evidence of an increase in injury rates by duration of infection. CONCLUSION: This is the first study to demonstrate an increase in injury rates in HIV-positive individuals. The increase may reflect direct effects of HIV infection as well as behaviour change once HIV is diagnosed.