The Role of Physical, Chemical, and Microbial Heterogeneity on the Field-Scale Transport and Attachment of Bacteria

A field-scale bacterial transport experiment was conducted at the Narrow Channel Focus Area of the South Oyster field site located in Oyster, Virginia. The goal of the field experiment was to determine the relative influence of subsurface heterogeneity and microbial population parameters on flow direction, velocity, and attachment of bacteria at the field scale. The field results were compared with results from laboratory-scale column experiments to develop a method for predicting field-scale bacterial transport. The field site is a shallow, sandy, unconfined, aerobic aquifer that has been characterized by geophysical, sedimentological, and hydrogeological methods. Comamonas sp. strain DA001 and a conservative tracer, bromide (Br), were injected into an area of high permeability for 12 hours. The Br and bacterial concentrations in the groundwater were monitored for 1 week at 192 sampling ports spaced over a 2-m vertical zone located from 0.5 to 7 m down-gradient of the injection well. The bacterial and Br plume was observed to move past 95 sampling ports. The densely characterized field site enabled the comparison of variations in DA001 transport to the aquifer properties. The velocity of the injected plume was correlated with geophysical estimates of hydraulic conductivity. The bacterial and Br plume appeared to follow flow paths not coincident with the hydraulic gradient but through a zone of higher permeability located off the flow axis. The amount of breakthrough of the bacteria was similar in both the high and low permeability layers with only a weak correlation between the observed hydraulic conductivity and amount of bacterial breakthrough. The uniformity in the observed attachment rates across varying grain sizes could be explained by heterogeneity of microbial properties within the single strain of injected bacteria. Application of colloid filtration theory to the field data indicated that variations in the microbial population were described by a lognormal distribution of the collision efficiency (a). Core-scale studies were used to predict the a distribution and field-scale transport distances of DA001. In sandy aquifers, physical heterogeneity may play a secondary role in controlling field-scale bacterial transport, and future research should focus on the microbial factors affecting transport

Ears of the Armadillo: Global Health Research and Neglected Diseases in Texas

Neglected tropical diseases (NTDs) have\ud been recently identified as significant public\ud health problems in Texas and elsewhere in\ud the American South. A one-day forum on the\ud landscape of research and development and\ud the hidden burden of NTDs in Texas\ud explored the next steps to coordinate advocacy,\ud public health, and research into a\ud cogent health policy framework for the\ud American NTDs. It also highlighted how\ud U.S.-funded global health research can serve\ud to combat these health disparities in the\ud United States, in addition to benefiting\ud communities abroad

Predictors of diagnostic yield in bronchoscopy: a retrospective cohort study comparing different combinations of sampling techniques

<p>Abstract</p> <p>Background</p> <p>The reported diagnostic yield from bronchoscopies in patients with lung cancer varies greatly. The optimal combination of sampling techniques has not been finally established.</p> <p>The objectives of this study were to find the predictors of diagnostic yield in bronchoscopy and to evaluate different combinations of sampling techniques.</p> <p>Methods</p> <p>All bronchoscopies performed on suspicion of lung malignancy in 2003 and 2004 were reviewed, and 363 patients with proven malignant lung disease were included in the study. Sampling techniques performed were biopsy, transbronchial needle aspiration (TBNA), brushing, small volume lavage (SVL), and aspiration of fluid from the entire procedure. Logistic regression analyses were adjusted for sex, age, endobronchial visibility, localization (lobe), distance from carina, and tumor size.</p> <p>Results</p> <p>The adjusted odds ratios (OR) with 95% confidence intervals (CI) for a positive diagnostic yield through all procedures were 17.0 (8.5–34.0) for endobronchial lesions, and 2.6 (1.3–5.2) for constriction/compression, compared to non-visible lesions; 3.8 (1.3–10.7) for lesions > 4 cm, 6.7 (2.1–21.8) for lesions 3–4 cm, and 2.5 (0.8–7.9) for lesions 2–3 cm compared with lesions <= 2 cm. The combined diagnostic yield of biopsy and TBNA was 83.7% for endobronchial lesions and 54.2% for the combined group without visible lesions. This was superior to either technique alone, whereas additional brushing, SVL, and aspiration did not significantly increase the diagnostic yield.</p> <p>Conclusion</p> <p>In patients with malignant lung disease, visible lesions and larger tumor size were significant predictors of higher diagnostic yield, after adjustment for sex, age, distance from carina, side and lobe. The combined diagnostic yield of biopsy and TBNA was significant higher than with either technique alone.</p

Holocene lake salinity changes in the Wimmera, southeastern Australia, provide evidence for millennial-scale climate variability

Palaeosalinity records for groundwater-influenced lakes in the southwest Murray Basin were constructed from an ostracod-based, weighted-averaging transfer function, supplemented with evidence from Campylodiscus clypeus (diatom), charophyte oogonia, Coxiella striata (gastropod), Elphidium sp. (foraminifera), Daphniopsis sp. ephippia (Cladocera), and brine shrimp (Parartemia zietziana) faecal pellets, the δ 18O of ostracods, and >130μm quartz sand counts. The chronology is based on optically stimulated luminescence and calibrated radiocarbon ages. Relatively wet conditions are marked by lower salinities between 9600yr and 5700yr ago, but mutually exclusive high- and low-salinity ostracod communities suggest substantial variability in effective precipitation in the early Holocene. A drier climate was firmly in place by 4500yr and is marked at the groundwater-dominated NW Jacka Lake by an increase in aeolian quartz and, at Jacka Lake, by a switch from surface-water to groundwater dominance. Short-lived, low-salinity events at 8800, 7200, 5900, 4800, 2400, 1300 and 400yr are similar in timing and number to those recorded on Australia's southern continental shelf, and globally, and provide evidence for the existence of the ~1500-yr cycle in mainland southern Australia. We surmise that these are cool events associated with periodic equatorward shifts in the westerly wind circulation

Holocene lake salinity changes in the Wimmera, southeastern Australia, provide evidence for millennial-scale climate variability

Palaeosalinity records for groundwater-influenced lakes in the southwest Murray Basin were constructed from an ostracod-based,weighted-averaging transfer function, supplemented with evidence fromCampylodiscus clypeu (diatom), charophyte oogonia, Coxiella striata (gastropod), Elphidium sp. (foraminifera), Daphniopsis sp. ephippia (Cladocera), and brine shrimp (Parartemia zietziana) faecal pellets, the δ18O of ostracods, and N130 μmquartz sand counts. The chronology is based on optically stimulated luminescence and calibrated radiocarbon ages. Relativelywet conditions aremarked by lower salinities between 9600 yr and 5700 yr ago, butmutually exclusive high- and low salinity ostracod communities suggest substantial variability in effective precipitation in the early Holocene. A drier climate was firmly in place by 4500 yr and is marked at the groundwater-dominated NW Jacka Lake by an increase in aeolian quartz and, at Jacka Lake, by a switch from surfacewater to groundwater dominance. Short lived, low-salinity events at 8800, 7200, 5900, 4800, 2400, 1300 and 400 yr are similar in timing and number to those recorded on Australia's southern continental shelf, and globally, and provide evidence for the existence of the ~1500-yr cycle in mainland southern Australia. We surmise that these are cool events associated with periodic equatorward shifts in the westerly wind circulation

A 1500 year record of coastal sediment accumulation preserved in beach deposits at Keppel Bay, Queensland, Australia

The coastal plain formed by a series of relict beach ridges on the margin of Keppel Bay, central Queensland, Australia, preserves a detailed record of coastal sediment accumulation. Importantly, this record spans the historical period and extends back to early Holocene times, well before European settlement. The relict and modern beach ridges comprise fine sand that was originally deposited in Keppel Bay during flood discharge events of the Fitzroy River. This sediment was then reworked onto the shoreline by the prevailing tide, wave and wind-generated currents. Optically stimulated luminescence (OSL) ages of the ridges reveal a long-term positive coastal sediment budget in Keppel Bay and show that during approximately the last 1500 years, sets of beach ridges were emplaced in rapid episodes, up to a few decades long. The OSL ages of the ridges suggests there is a 500-200 yr periodicity to these phases of rapid sediment accumulation. Our preliminary interpretation of these data is that this pattern of formation relates to the recurrence interval of high magnitude flood discharge events of the Fitzroy River and there has been a general decline in the rate at which sediment has accumulated on the Keppel Bay coast during the last 1500 years. This reduction may reflect a long-term decline in major rainfall events in the Fitzroy River catchment. The trace element composition of ridges deposited during the last 100 yrs indicates there has been a greater contribution from areas of basaltic soils within the catchment. This trace-element record reveals the impact on river and coastal sediment composition brought on by changes in catchment land use

Using Model-Based Screening to Help Discover Unknown Environmental Contaminants

Of the tens of thousands of chemicals in use, only a small fraction have been analyzed in environmental samples. To effectively identify environmental contaminants, methods to prioritize chemicals for analytical method development are required. We used a high-throughput model of chemical emissions, fate, and bioaccumulation to identify chemicals likely to have high concentrations in specific environmental media, and we prioritized these for target analysis. This model-based screening was applied to 215 organosilicon chemicals culled from industrial chemical production statistics. The model-based screening prioritized several recognized organosilicon contaminants and generated hypotheses leading to the selection of three chemicals that have not previously been identified as potential environmental contaminants for target analysis. Trace analytical methods were developed, and the chemicals were analyzed in air, sewage sludge, and sediment. All three substances were found to be environmental contaminants. Phenyl-tris­(trimethylsiloxy)­silane was present in all samples analyzed, with concentrations of ∼50 pg m^–3 in Stockholm air and ∼0.5 ng g^–1 dw in sediment from the Stockholm archipelago. Tris­(trifluoropropyl)­trimethyl-cyclotrisiloxane and tetrakis­(trifluoropropyl)­tetramethyl-cyclotetrasiloxane were found in sediments from Lake Mjøsa at ∼1 ng g^–1 dw. The discovery of three novel environmental contaminants shows that models can be useful for prioritizing chemicals for exploratory assessment