Gaseous elemental mercury depletion events observed at Cape Point during 2007–2008

Gaseous mercury in the marine boundary layer has been measured with a 15 min temporal resolution at the Global Atmosphere Watch station Cape Point since March 2007. The most prominent features of the data until July 2008 are the frequent occurrences of pollution (PEs) and depletion events (DEs). Both types of events originate mostly within a short transport distance (up to about 100 km), which are embedded in air masses ranging from marine background to continental. The Hg/CO emission ratios observed during the PEs are within the range reported for biomass burning and industrial/urban emissions. The depletion of gaseous mercury during the DEs is in many cases almost complete and suggests an atmospheric residence time of elemental mercury as short as a few dozens of hours, which is in contrast to the commonly used estimate of approximately 1 year. The DEs observed at Cape Point are not accompanied by simultaneous depletion of ozone which distinguishes them from the halogen driven atmospheric mercury depletion events (AMDEs) observed in Polar Regions. Nonetheless, DEs similar to those observed at Cape Point have also been observed at other places in the marine boundary layer. Additional measurements of mercury speciation and of possible mercury oxidants are hence called for to reveal the chemical mechanism of the newly observed DEs and to assess its importance on larger scales

Deriving projects from the organisational vision using the Vision-to-Projects (V2P) Framework

Organisations initiate and execute projects at an ever-increasing ratein order to achieve their strategic intentions. Many of these, however,find it difficult to measure the contribution that these projects maketowards the realisation of the organisational vision. In order to effectthese changes in a cumulatively beneficial way, a holistic approachis needed. The Vision-to-Projects (V2P) Framework was developed tofacilitate such an approach and can be applied to all organisationaltypes. This article shows how participatory action research was appliedin the development of the V2P Framework. While largely validatingthe theoretical framework, it did indeed reveal several beneficialmodifications to improve its applicability. The main results of this research are twofold. It firstly provides organisations with a framework that can be used to derive projects from the organisational vision and strategies, thereby ensuring continuous alignment. Secondly, it shows the successful use of participatory action research in the field of project management thathas been dominated, thus far, by quantitative research methods

Continuous measurements of greenhouse gases and atmospheric oxygen at the Namib Desert atmospheric observatory

A new coastal background site has been established for observations of greenhouse gases (GHGs) in the central Namib Desert at Gobabeb, Namibia. The location of the site was chosen to provide observations for a data-poor region in the global sampling network for GHGs. Semi-automated continuous measurements of carbon dioxide, methane, nitrous oxide, carbon monoxide, atmospheric oxygen, and basic meteorology are made at a height of 21 m a.g.l., 50 km from the coast at the northern border of the Namib Sand Sea. Atmospheric oxygen is measured with a differential fuel cell analyzer (DFCA). Carbon dioxide and methane are measured with an early-model cavity ring-down spectrometer (CRDS); nitrous oxide and carbon monoxide are measured with an off-axis integrated cavity output spectrometer (OA-ICOS). Instrument-specific water corrections are employed for both the CRDS and OA-ICOS instruments in lieu of drying. The performance and measurement uncertainties are discussed in detail. As the station is located in a remote desert environment, there are some particular challenges, namely fine dust, high diurnal temperature variability, and minimal infrastructure. The gas handling system and calibration scheme were tailored to best fit the conditions of the site. The CRDS and DFCA provide data of acceptable quality when base requirements for operation are met, specifically adequate temperature control in the laboratory and regular supply of electricity. In the case of the OA-ICOS instrument, performance is significantly improved through the implementation of a drift correction through frequent measurements of a reference cylinder

One-carbon metabolism in cancer

Cells require one-carbon units for nucleotide synthesis, methylation and reductive metabolism, and these pathways support the high proliferative rate of cancer cells. As such, anti-folates, drugs that target one-carbon metabolism, have long been used in the treatment of cancer. Amino acids, such as serine are a major one-carbon source, and cancer cells are particularly susceptible to deprivation of one-carbon units by serine restriction or inhibition of de novo serine synthesis. Recent work has also begun to decipher the specific pathways and sub-cellular compartments that are important for one-carbon metabolism in cancer cells. In this review we summarise the historical understanding of one-carbon metabolism in cancer, describe the recent findings regarding the generation and usage of one-carbon units and explore possible future therapeutics that could exploit the dependency of cancer cells on one-carbon metabolism

Abnormal visual scanning of emotionally evocative natural scenes in Huntington's disease

Huntington’s disease (HD) is a neurodegenerative movement disorder associated with deficits in the processing of emotional stimuli, including alterations in the self-reported subjective experience of emotion when presented with pictures of emotional scenes. The aim of this study was to determine whether individuals with HD, compared to unaffected controls, display abnormal visual scanning of emotionally evocative natural scenes. Using eye-tracking, we recorded eye-movements of 25 HD participants (advanced pre-symptomatic and early symptomatic) and 25 age-matched unaffected control participants during a picture viewing task. Participants viewed pictures of natural scenes associated with different emotions: anger, fear, disgust, happiness, or neutral, and evaluated those pictures on a valence rating scale. Individuals with HD displayed abnormal visual scanning patterns, but did not differ from controls with respect to their valence ratings. Specifically, compared to controls, HD participants spent less time fixating on the pictures and made longer scan paths. This finding highlights the importance of taking visual scanning behavior into account when investigating emotion processing in HD. The visual scanning patterns displayed by HD participants could reflect a heightened, but possibly unfocussed, search for information, and might be linked to attentional deficits or to altered subjective emotional experiences in HD. Another possibility is that HD participants may have found it more difficult than controls to evaluate the emotional valence of the scenes, and the heightened search for information was employed as a compensatory strategy

Visuospatial Processing Deficits Linked to Posterior Brain Regions in Premanifest and Early Stage Huntington's Disease.

OBJECTIVES: Visuospatial processing deficits have been reported in Huntington's disease (HD). To date, no study has examined associations between visuospatial cognition and posterior brain findings in HD. METHODS: We compared 119 premanifest (55> and 64<10.8 years to expected disease onset) and 104 early symptomatic (59 stage-1 and 45 stage-2) gene carriers, with 110 controls on visual search and mental rotation performance at baseline and 12 months. In the disease groups, we also examined associations between task performance and disease severity, functional capacity and structural brain measures. RESULTS: Cross-sectionally, there were strong differences between all disease groups and controls on visual search, and between diagnosed groups and controls on mental rotation accuracy. Only the premanifest participants close to onset took longer than controls to respond correctly to mental rotation. Visual search negatively correlated with disease burden and motor symptoms in diagnosed individuals, and positively correlated with functional capacity. Mental rotation ("same") was negatively correlated with motor symptoms in stage-2 individuals, and positively correlated with functional capacity. Visual search and mental rotation were associated with parieto-occipital (pre-/cuneus, calcarine, lingual) and temporal (posterior fusiform) volume and cortical thickness. Longitudinally, visual search deteriorated over 12 months in stage-2 individuals, with no evidence of declines in mental rotation. CONCLUSIONS: Our findings provide evidence linking early visuospatial deficits to functioning and posterior cortical dysfunction in HD. The findings are important since large research efforts have focused on fronto-striatal mediated cognitive changes, with little attention given to aspects of cognition outside of these areas. (JINS, 2016, 22, 595-608)

Visuospatial Processing Deficits Linked to Posterior Brain Regions in Premanifest and Early Stage Huntington's Disease

OBJECTIVES: Visuospatial processing deficits have been reported in Huntington’s disease (HD). To date, no study has examined associations between visuospatial cognition and posterior brain findings in HD. METHODS: We compared 119 premanifest (55> and 64<10.8 years to expected disease onset) and 104 early symptomatic (59 stage-1 and 45 stage-2) gene carriers, with 110 controls on visual search and mental rotation performance at baseline and 12 months. In the disease groups, we also examined associations between task performance and disease severity, functional capacity and structural brain measures. RESULTS: Cross-sectionally, there were strong differences between all disease groups and controls on visual search, and between diagnosed groups and controls on mental rotation accuracy. Only the premanifest participants close to onset took longer than controls to respond correctly to mental rotation. Visual search negatively correlated with disease burden and motor symptoms in diagnosed individuals, and positively correlated with functional capacity. Mental rotation (“same”) was negatively correlated with motor symptoms in stage-2 individuals, and positively correlated with functional capacity. Visual search and mental rotation were associated with parieto-occipital (pre-/cuneus, calcarine, lingual) and temporal (posterior fusiform) volume and cortical thickness. Longitudinally, visual search deteriorated over 12 months in stage-2 individuals, with no evidence of declines in mental rotation. Conclusions: Our findings provide evidence linking early visuospatial deficits to functioning and posterior cortical dysfunction in HD. The findings are important since large research efforts have focused on fronto-striatal mediated cognitive changes, with little attention given to aspects of cognition outside of these areas. (JINS, 2016, 22, 595–608

Risk stratification of hospital admissions for COVID-19 pneumonia by chest radiographic scoring in a Johannesburg tertiary hospital

Background. Chest radiographic scoring systems for COVID-19 pneumonia have been developed. However, little is published on the utilityof these scoring systems in low- and middle-income countries.Objectives. To perform risk stratification of COVID-19 pneumonia in Johannesburg, South Africa (SA), by comparing the Brixia score withclinical parameters, disease course and clinical outcomes. To assess inter-rater reliability and developing predictive models of the clinicaloutcome using the Brixia score and clinical parameters.Methods. Retrospective investigation was conducted of adult participants with established COVID-19 pneumonia admitted at a tertiaryinstitution from 1 May to 30 June 2020. Two radiologists, blinded to clinical data, assigned Brixia scores. Brixia scores were compared withclinical parameters, length of stay and clinical outcomes (discharge/death). Inter-rater agreement was determined. Multivariable logisticregression extracted variables predictive of in-hospital demise.Results. The cohort consisted of 263 patients, 51% male, with a median age of 47 years (interquartile range (IQR) = 20; 95% confidenceinterval (CI) 46.5 - 49.9). Hypertension (38.4%), diabetes (25.1%), obesity (19.4%) and HIV (15.6%) were the most common comorbidities.The median length of stay for 258 patients was 7.5 days (IQR = 7; 95% CI 8.2 - 9.7) and 6.5 days (IQR = 8; 95% CI 6.5 - 12.5) for intensivecare unit stay. Fifty (19%) patients died, with a median age of 55 years (IQR = 23; 95% CI 50.5 - 58.7) compared with survivors, of medianage 46 years (IQR = 20; 95% CI 45 - 48.6) (p=0.01). The presence of one or more comorbidities resulted in a higher death rate (23% v. 9.2%;p=0.01) than without comorbidities. The median Brixia score for the deceased was higher (14.5) than for the discharged patients (9.0)(p&lt;0.001). Inter-rater agreement for Brixia scores was good (intraclass correlation coefficient 0.77; 95% CI 0.6 - 0.85; p&lt;0.001). A modelcombining Brixia score, age, male gender and obesity (sensitivity 84%; specificity 63%) as well as a model with Brixia score and C-reactiveprotein (CRP) count (sensitivity 81%; specificity 63%) conferred the highest risk for in-hospital mortality.Conclusion. We have demonstrated the utility of the Brixia scoring system in a middle-income country setting and developed the first SArisk stratification models incorporating comorbidities and a serological marker. When used in conjunction with age, male gender, obesityand CRP, the Brixia scoring system is a promising and reliable risk stratification tool. This may help inform the clinical decision pathway inresource-limited settings like ours during future waves of COVID-19