Tracing enteric pathogen contamination in sub-Saharan African groundwater

Quantitative PCR (qPCR) can rapidly screen for an array of faecally-derived bacteria, which can be employed as tracers to understand groundwater vulnerability to faecal contamination. A microbial DNA qPCR array was used to examine 45 bacterial targets, potentially relating to enteric pathogens, in 22 groundwater supplies beneath the city of Kabwe, Zambia in both the dry and subsequent wet season. Thermotolerant (faecal) coliforms, sanitary risks, and tryptophan-like fluorescence, an emerging real-time reagentless faecal indicator, were also concurrently investigated. There was evidence for the presence of enteric bacterial contamination, through the detection of species and group specific 16S rRNA gene fragments, in 72% of supplies where sufficient DNA was available for qPCR analysis. DNA from the opportunistic pathogen Citrobacter freundii was most prevalent (69% analysed samples), with Vibrio cholerae also perennially persistent in groundwater (41% analysed samples). DNA from other species such as Bifidobacterium longum and Arcobacter butzleri was more seasonally transient. Bacterial DNA markers were most common in shallow hand-dug wells in laterite/saprolite implicating rapid subsurface pathways and vulnerability to pollution at the surface. Boreholes into the underlying dolomites were also contaminated beneath the city highlighting that a laterite/saprolite overburden, as occurs across much of sub-Saharan aquifer, does not adequately protect underlying bedrock groundwater resources. Nevertheless, peri-urban boreholes all tested negative establishing there is limited subsurface lateral transport of enteric bacteria outside the city limits. Thermotolerant coliforms were present in 97% of sites contaminated with enteric bacterial DNA markers. Furthermore, tryptophan-like fluorescence was also demonstrated as an effective indicator and was in excess of 1.4 μg/L in all contaminated sites

In-situ tryptophan-like fluorescence: a real-time indicator of faecal contamination in drinking water supplies

Enteric pathogens are typically inferred from the presence of surrogate indicator organisms such as thermo-tolerant (faecal) coliforms (TTCs). The analysis of TTCs requires time-consuming incubation in suitable laboratories, which can limit sampling resolution, particularly during critical pollution events. Here, we demonstrate the use of in-situ fluorimeters targeting tryptophan-like compounds as a rapid, reagentless indicator of TTCs in groundwater-derived potable water supplies in Africa. A range of other common indicators of TTCs were also determined including nitrate, turbidity, and sanitary risk survey scores. Sampling was conducted during both the dry and wet seasons to investigate seasonality. Tryptophan-like fluorescence was the most effective predictor of both presence/absence and number of TTCs during both seasons. Seasonal changes in tryptophan-like fluorescence in deeper supplies suggest it is transported more efficiently through the aquifer than TTCs. Moreover, the perennial elevated concentrations in some wells suggest it is more resilient than TTCs in groundwater. Therefore tryptophan-like fluorescence could also be a better indicator of some smaller, more easily transported, and long-lived, pathogenic enteric viruses. These sensors have the potential to be included in real-time pollutionalert systems for drinking water supplies throughout the world, as well as for mapping enteric pathogen risks in developing regions

Emerging contaminants in urban groundwater sources in Africa

The occurrence of emerging organic contaminants within the aquatic environment in Africa is currently unknown. This study provides early insights by characterising a broad range of emerging organic contaminants (n > 1000) in groundwater sources in Kabwe, Zambia. Groundwater samples were obtained during both the dry and wet seasons from a selection of deep boreholes and shallow wells completed within the bedrock and overlying superficial aquifers, respectively. Groundwater sources were distributed across the city to encompass peri-urban, lower cost housing, higher cost housing, and industrial land uses. The insect repellent DEET was ubiquitous within groundwater at concentrations up to 1.8 mg/L. Other compounds (n ¼ 26) were detected in less than 15% of the sources and included the bactericide triclosan (up to 0.03 mg/L), chlorination by-products e trihalomethanes (up to 50 mg/L), and the surfactant 2,4,7,9-tetramethyl-5-decyne-4,7-diol (up to 0.6 mg/L). Emerging contaminants were most prevalent in shallow wells sited in low cost housing areas. This is attributed to localised vulnerability associated with inadequate well protection, sanitation, and household waste disposal. The five-fold increase in median DEET concentration following the onset of the seasonal rains highlights that more mobile compounds can rapidly migrate from the surface to the aquifer suggesting the aquifer is more vulnerable than previously considered. Furthermore it suggests DEET is potentially useful as a wastewater tracer in Africa. There was a general absence of personal care products, life-style compounds, and pharmaceuticals which are commonly detected in the aquatic environment in the developed world. This perhaps reflects some degree of attenuation within the subsurface, but could also be a result of the current limited use of products containing emerging contaminants by locals due to unaffordability and unavailability. As development and population increases in Africa, it is likely a wider-range of emerging contaminants will be released into the environment

Disordered Hubbard Model with Attraction: Coupling Energy of Cooper Pairs in Small Clusters

We generalize the Cooper problem to the case of many interacting particles in the vicinity of the Fermi level in the presence of disorder. On the basis of this approach we study numerically the variation of the pair coupling energy in small clusters as a function of disorder. We show that the Cooper pair energy is strongly enhanced by disorder, which at the same time leads to the localization of pairs.Comment: revtex, 5 pages, 6 figure

Strangeness Enhancement in p-A Collisions: Consequences for the Interpretation of Strangeness Production in A-A Collisions

Published measurements of semi-inclusive Lambda production in p-Au collisions at the AGS are used to estimate the yields of singly strange hadrons in nucleus-nucleus A-A collisions. Results of a described extrapolation technique are shown and compared to measurements of K+ production in Si-Al, Si-Au, and Au-Au collisions at the AGS and net Lambda production in Su-Su, S-Ag, Pb-Pb, and inclusive p-A collisions at the SPS. The extrapolations can account for more than 75% of the measured strange particle yields in all of the studied systems except for very central Au-Au collisions at the AGS where RQMD comparisons suggest large re-scattering contributions.Comment: 9 pages, 4 figure

Measuring neutrino masses with a future galaxy survey

We perform a detailed forecast on how well a Euclid-like photometric galaxy and cosmic shear survey will be able to constrain the absolute neutrino mass scale. Adopting conservative assumptions about the survey specifications and assuming complete ignorance of the galaxy bias, we estimate that the minimum mass sum of sum m_nu ~ 0.06 eV in the normal hierarchy can be detected at 1.5 sigma to 2.5 sigma significance, depending on the model complexity, using a combination of galaxy and cosmic shear power spectrum measurements in conjunction with CMB temperature and polarisation observations from Planck. With better knowledge of the galaxy bias, the significance of the detection could potentially reach 5.4 sigma. Interestingly, neither Planck+shear nor Planck+galaxy alone can achieve this level of sensitivity; it is the combined effect of galaxy and cosmic shear power spectrum measurements that breaks the persistent degeneracies between the neutrino mass, the physical matter density, and the Hubble parameter. Notwithstanding this remarkable sensitivity to sum m_nu, Euclid-like shear and galaxy data will not be sensitive to the exact mass spectrum of the neutrino sector; no significant bias (< 1 sigma) in the parameter estimation is induced by fitting inaccurate models of the neutrino mass splittings to the mock data, nor does the goodness-of-fit of these models suffer any significant degradation relative to the true one (Delta chi_eff ^2< 1).Comment: v1: 29 pages, 10 figures. v2: 33 pages, 12 figures; added sections on shape evolution and constraints in more complex models, accepted for publication in JCA

Poor nutritional status is associated with other geriatric domain impairments and adverse postoperative outcomes in onco-geriatric surgical patients – a multicentre cohort study

Background: Nutritional status (NS), though frequently affected in onco-geriatric patients, is no standard part of a geriatric assessment. The aim of this study was to analyse the association between a preoperatively impaired NS and geriatric domain impairments and adverse postoperative outcomes in onco-geriatric surgical patients. Methods: 309 patients ≥70 years undergoing surgery for solid tumours were prospectively recruited. Nine screening tools were preoperatively administered as part of a geriatric assessment. NS was based on BMI, weight loss and food intake. Odds ratio’s (OR) and 95% confidence intervals (95%CI) were estimated using logistic regression analysis. The occurrence of 30-day adverse postoperative outcomes was recorded. Results: At a median age of 76 years, 107 patients (34.6%) had an impaired NS. Decreased performance status and depression were associated with an impaired NS, when adjusted for tumour characteristics and comorbidities (ORPS>1 3.46; 95%CI 1.56-7.67. ORGDS>5 2.11; 95%CI 1.05-4.26). An impaired NS was an independent predictor for major complications (OR 3.3; 95%CI 1.6-6.8). Ten out of 11 patients who deceased had an impaired NS. Conclusion: An impaired NS is prevalent in onco-geriatric patients considered to be fit for surgery. It is associated with decreased performance status and depression. An impaired NS is a predictor for adverse postoperative outcomes. NS should be incorporated in a geriatric assessment

Moorean Absurdities and the Nature of Assertion

10.1080/00048409612347111Australasian Journal of Philosophy741135-14