The performance of air sparging systems, as measured by the predicted region of airflow, was investigated by conducting numerical simulations with a multiphase modeling program (TETRAD). The ...simulations employed standard two-phase flow theory, and included pressure-dependent calculations of the compressibility of water and air. Simulations tested the response of air sparging systems to variations in geological properties (intrinsic permeability and anisotropy of permeability) as well as different injection scenarios (depth, pressure, and rate of injection). Three stages of flow behavior are predicted following initiation of air injection. These are: (1) an initial transient period of growth in the lateral and vertical limits of airflow (expansion stage); (2) a second transient period of reduction in the lateral limits of airflow (collapse stage); and (3) a steady-state stage, during which the system remains static as long as injection parameters do not change. In homogeneous media the geometry of the region of airflow changes from a teardrop- or bell-shaped configuration to a shape that is roughly conical during the expansion stage. During the collapse stage, air is preferentially diverted to established regions of high effective air permeability, and ground water resaturates the remainder of the original region of influence. For pilot testing it is important to realize that measurements of the lateral extent of airflow expansion and collapse stages can be misleading because they will differ from the limits established at steady-state. The time required for a particular system to progress through the transient stages and establish steady-state behavior can vary from hours to years, and is dependent on the permeability structure of the aquifer, injection depth, and injection rate. Under homogeneous conditions the maximum width of the region of airflow attained during the transient expansion stage was substantially greater than the width attained at steady-state
In a media environment that is increasingly defined by the trendiness that afflicts a whole bunch of other categories, brands run the risk of looking like an outsider trying to seem with it, unsure ...of why they're there or what they're supposed to do to become a valuable member of the community. Media innovation is happening in quantity, form and function like never before. For the media-defined generation, new properties, content and applications have social currency in the discovery. There are examples across the marketing universe where brands and their agencies have jumped into trendy environments to do trendy things. But they're not really sure why or what the real payback will be.
In order to understand the dynamic environment incurred by the on-orbit replacement Hubble Space Telescope solar arrays, two on-orbit forcing function tests were conducted shortly after the ...spacecraft servicing mission. These tests were necessitated by the fact that even with the new solar arrays, spacecraft jitter exceeded the spacecraft's extremely tight pointing requirements. The first test was conducted to determine the modal frequencies of interest. The second test was conducted to determine the gain and damping for the spacecraft significant modes. The data from the second test was reduced and a set of modal gains and damping was developed; this spacecraft model has been verified through observation of flight data. Using this new plant data, compensation is presented in this article which attenuates the spacecraft jitter associated with the spacecraft modes.
Back in the mid 2000's coal fired electric utilities, primarily in the eastern half of the US, basked in an era of limited regulatory uncertainty. The Environmental Protection Agency's Clean Air ...Interstate Rule had not yet been overturned by the courts and the train wreck of other regulatory initiatives was but a faint and cloudy worry on the utility planner's horizon. A number of utilities, including Southern Co, began to explore a non-traditional design strategy whereby they could eliminate the cost of the entire limestone receiving, storage and wet milling facilities at several plants within the same geographic region and replace them with pre-ground limestone from an outside supplier. Southern's project engineers and procurement analysts compared the traditional wet ball mill approach with the pre-pulverized option for various plants in their system, at times concluding that pre-pulverized reagent was the better operational and economic choice. As a result, they entered into pulverized limestone supply agreements.
The impact of air pollution on human health and the associated external costs in Europe and the United States (US) for the year 2010 are modeled by a multi-model ensemble of regional models in the ...frame of the third phase of the Air Quality Modelling Evaluation International Initiative (AQMEII3). The modeled surface concentrations of O
, CO, SO
and PM
are used as input to the Economic Valuation of Air Pollution (EVA) system to calculate the resulting health impacts and the associated external costs from each individual model. Along with a base case simulation, additional runs were performed introducing 20 % anthropogenic emission reductions both globally and regionally in Europe, North America and east Asia, as defined by the second phase of the Task Force on Hemispheric Transport of Air Pollution (TF-HTAP2). Health impacts estimated by using concentration inputs from different chemistry-transport models (CTMs) to the EVA system can vary up to a factor of 3 in Europe (12 models) and the United States (3 models). In Europe, the multi-model mean total number of premature deaths (acute and chronic) is calculated to be 414 000, while in the US, it is estimated to be 160 000, in agreement with previous global and regional studies. The economic valuation of these health impacts is calculated to be EUR 300 billion and 145 billion in Europe and the US, respectively. A subset of models that produce the smallest error compared to the surface observations at each time step against an all-model mean ensemble results in increase of health impacts by up to 30 % in Europe, while in the US, the optimal ensemble mean led to a decrease in the calculated health impacts by ~ 11 %. A total of 54 000 and 27 500 premature deaths can be avoided by a 20 % reduction of global anthropogenic emissions in Europe and the US, respectively. A 20 % reduction of North American anthropogenic emissions avoids a total of ~ 1000 premature deaths in Europe and 25 000 total premature deaths in the US. A 20 % decrease of anthropogenic emissions within the European source region avoids a total of 47 000 premature deaths in Europe. Reducing the east Asian anthropogenic emissions by 20 % avoids ~ 2000 total premature deaths in the US. These results show that the domestic anthropogenic emissions make the largest impacts on premature deaths on a continental scale, while foreign sources make a minor contribution to adverse impacts of air pollution.
Organic biomarker distribution and stable isotope composition was used to investigate biogeochemical carbon cycling in the anoxic basin of Lake Untersee, Antarctica. Phospholipid fatty acid (PLFA) ...concentrations indicative of microbial abundances were low in the oxic water column overlying the basin but rose in the suboxic transition zone and further increased within the underlying anoxic water, with the highest abundances near the sediment water interface. Archaeol (up to 24.8 mg/kg) and glycerol dialkyl glycerol tetraethers were only detected within the deepest water sample and sediment. High methane (CH
4
) concentrations (ca. 172 mg/L or 11 mmol/L) were observed in the deepest water samples and produced via hydrogenotrophy (CO
2
-reduction) based on methane isotopes and highly
13
C-enriched dissolved inorganic carbon. Methane concentration slowly decreased away from the sediment, across the anoxic water column and then decreased rapidly at the oxic/anoxic interface (78–68 m). Here a ca. 10‰
increase
in δ
13
C
CH4
values combined with δ
13
C
PLFA
values that
decreased
as CH
4
concentrations rapidly declined indicated an aerobic methanotrophy fueled microbial community. Findings suggest that upward methane diffusion drives microbial productivity within the suboxic/anoxic zones resulting in the observed high PLFA biomass. Subsequent sinking of detrital material from these communities supports heterotrophic microbes throughout the anoxic water column and potentially supplied nutrients to support phototrophy in the upper suboxic transition zone, itself contributing to sinking detrital material and accumulation of sedimentary organic material. Notably, while a clear biosignature of methane oxidation is present in suboxic zone PLFA, this signature is not recognizable within the sediments.
The harbour seal (Phoca vitulina) is the most widely distributed pinniped, occupying a wide variety of habitats and climatic zones across the Northern Hemisphere. Intriguingly, the harbour seal is ...also one of the most philopatric seals, raising questions as to how it colonized its current range. To shed light on the origin, remarkable range expansion, population structure and genetic diversity of this species, we used genotyping‐by‐sequencing to analyse ~13,500 biallelic single nucleotide polymorphisms from 286 individuals sampled from 22 localities across the species’ range. Our results point to a Northeast Pacific origin of the harbour seal, colonization of the North Atlantic via the Canadian Arctic, and subsequent stepping‐stone range expansions across the North Atlantic from North America to Europe, accompanied by a successive loss of genetic diversity. Our analyses further revealed a deep divergence between modern North Pacific and North Atlantic harbour seals, with finer‐scale genetic structure at regional and local scales consistent with strong philopatry. The study provides new insights into the harbour seal's remarkable ability to colonize and adapt to a wide range of habitats. Furthermore, it has implications for current harbour seal subspecies delineations and highlights the need for international and national red lists and management plans to ensure the protection of genetically and demographically isolated populations.
DNA from low-biodiversity fracture water collected at 2.8-kilometer depth in a South African gold mine was sequenced and assembled into a single, complete genome. This bacterium, Candidatus ...Desulforudis audaxviator, composes >99.9% of the microorganisms inhabiting the fluid phase of this particular fracture. Its genome indicates a motile, sporulating, sulfate-reducing, chemoautotrophic thermophile that can fix its own nitrogen and carbon by using machinery shared with archaea. Candidatus Desulforudis audaxviator is capable of an independent life-style well suited to long-term isolation from the photosphere deep within Earth's crust and offers an example of a natural ecosystem that appears to have its biological component entirely encoded within a single genome.
Parkinson's disease (PD) is a disorder affecting dopamine neurons for which there is no cure. Glial cell line-derived neurotrophic factor (GDNF) and the closely related protein neurturin are two ...trophic factors with demonstrated neuroprotective and neurorestorative properties on dopamine neurons in multiple animal species. However, GDNF and neurturin Phase-2 clinical trials have failed to demonstrate a significant level of improvement over placebo controls. Insufficient drug distribution in the brain parenchyma has been proposed as a major contributing factor for the lack of clinical efficacy in the Phase-2 trial patients. To address this issue, a novel mammalian cell-derived variant form of GDNF (GDNFv) was designed to promote better tissue distribution by reducing its heparin binding to the extracellular matrix and key amino acids were substituted to enhance its chemical stability. Administration of this fully glycosylated GDNFv in the normal rat striatum increased dopamine turnover and produced significantly greater brain distribution than E. coli-produced wildtype GDNF (GDNFwt). Intrastriatal GDNFv also protected midbrain dopamine neuron function in 6-hydroxydopamine-lesioned rats. Studies conducted in normal adult rhesus macaques support that GDNFv was well tolerated in all animals and demonstrated a greater volume of distribution than GDNFwt in the brain following intrastriatal infusion. Importantly, favorable physiological activity of potential therapeutic value was maintained in this variant trophic factor with significant target activation in GDNFv recipients as indicated by dopamine turnover modulation. These data suggest that GDNFv may be a promising drug candidate for the treatment of PD. Additional studies are needed in non-human primates with dopamine depletion.
This article is part of the Special Issue entitled ‘Drug Repurposing: old molecules, new ways to fast track drug discovery and development for CNS disorders’.
•Neurotrophic factors have great therapeutic potential for Parkinson's disease.•Insufficient brain distribution has limited the clinical use of trophic factors.•A variant form of GDNF shows increased dopamine turnover and brain bioavailability.•GDNF variant is well tolerated in treated animals.•GDNF variant represents a promising drug candidate for treating parkinsonian patients.
Abstract Introduction Non-arteritic anterior ischemic optic neuropathy (NAION) is the most common optic neuropathy in middle-aged and older-aged adult. There are an estimated 6000 new cases per year ...and is most commonly diagnosed in patients between 61-72 years of age. It affects men and women equally. There is a slightly higher incidence in white patients. 55-59% of patients with NAION also have OSA. Report of case(s) A 51-year-old man with a past medical history of hypertension and erectile dysfunction developed painless left inferior altitudinal visual field loss and blurriness in April 2023. He was seen in the Ophthalmology Department and was found to have left unilateral optic disc swelling on fundoscopic examination. An MRI of his brain, orbits, and face were normal. He was referred to Neuro-Ophthalmology where a slit lamp and fundus exam was performed and was significant for 360 degrees of disc swelling with heme seen inferiorly and normal appearing vessels and macula. A follow up fundoscopic examination one month later was significant for a hyperemic nerve and nasal blurriness in the left eye. No changes were seen in the right eye. Based on these findings, he was diagnosed with NAION. A HST was ordered by his Ophthalmologist that showed moderate OSA with an AHI of 24.3/h, an O2 nadir of 81%, and an ODI of 32.3. He was then seen in the Sleep Medicine clinic and prescribed CPAP. At his two month follow up appointment, he had an improvement in his daytime sleepiness and concentration but still had residual visual deficits in his left eye, including blurriness, light sensitivity, and difficulty focusing. Conclusion NAION is a rare condition with untreated OSA as a known risk factor due to nocturnal hypoxia decreasing perfusion to the optic nerve. This case reinforces the notion that the hypoxic burden of untreated OSA is a systemic problem and can lead to damage throughout the body. In this case, the benefit of treating this patient’s OSA is that his contralateral eye, the right eye, is also vulnerable to developing the same ischemic optic neuropathy that the left eye suffered from. Support (if any)
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