198 research outputs found
Shale oil : potential economies of large-scale production, preliminary phase
Producing shale oil on a large scale is one of the possible
alternatives for reducing dependence of the United States on imported
petroleum. Industry is not producing shale oil on a commercial scale now
because costs are too high even though industry dissatisfaction is most
frequently expressed about "non-economic" barriers: innumerable permits,
changing environmental regulations, lease limitations, water rights
conflicts, legal challenges, and so on. The overall purpose of this
study is to estimate whether improved technology might significantly
reduce unit costs for production of shale oil in a planned large-scale
industry as contrasted to the case usually contemplated: a small
industry evolving slowly on a project-by-project basis.
In this preliminary phase of the study, we collected published data
on the costs of present shale oil technology and adjusted them to common
conditions; these data were assembled to help identify the best targets
for cost reduction through improved large-scale technology They show
that the total cost of producing upgraded shale oil (i.e. shale oil
accpetable as a feed to a petroleum refinery) by surface retorting ranges
from about 28/barrel in late '78 dollars with a 20% chance that
the costs would be lower than and 20% higher than that range. The
probability distribution reflects our assumptions about ranges of shale
richness, process performance, rate of return, and other factors that
seem likely in a total industry portfolio of projects.
About 40% of the total median cost is attributable to retorting, 20%
to upgrading, and the remaining 40% to resource acquisition, mining,
crushing, and spent shale disposal and revegetation. Capital charges account for about 70% of the median total cost and operating costs for
the other 30%.
There is a reasonable chance that modified in-situ processes (like
Occidental's) may be able to produce shale oil more cheaply than surface
retorting, but no reliable cost data have been published; in 1978, DOE
estimated a saving of roughly $5/B for in-situ.
Because the total costs of shale oil are spread over many steps in
the production process, improvements in most or all of those steps are
required if we seek a significant reduction in total cost. A June 1979
workshop of industry experts was held to help us identify possible
cost-reduction technologies. Examples of the improved large-scale
technologies proposed (for further evaluation) to the workshop were:
- Instead of hydrotreating raw shale oil to make syncrude capable of
being refined conventionally, rebalance all of a refinery's
processes (or develop new catalysts/processes less sensitive to
feed nitrogen) to accommodate shale oil feed -- a change analogous
to a shift from sweet crude to sour crude.
- Instead of refining at or near the retort site, use heated
pipelines to move raw shale oil to existing major refining areas.
- Instead of operating individual mines, open-pit mine all or much
of the Piceance Creek Basin.
- Instead of building individual retorts, develop new methods for
mass production of hundreds of retorts
CNN Architectures for Large-Scale Audio Classification
Convolutional Neural Networks (CNNs) have proven very effective in image
classification and show promise for audio. We use various CNN architectures to
classify the soundtracks of a dataset of 70M training videos (5.24 million
hours) with 30,871 video-level labels. We examine fully connected Deep Neural
Networks (DNNs), AlexNet [1], VGG [2], Inception [3], and ResNet [4]. We
investigate varying the size of both training set and label vocabulary, finding
that analogs of the CNNs used in image classification do well on our audio
classification task, and larger training and label sets help up to a point. A
model using embeddings from these classifiers does much better than raw
features on the Audio Set [5] Acoustic Event Detection (AED) classification
task.Comment: Accepted for publication at ICASSP 2017 Changes: Added definitions of
mAP, AUC, and d-prime. Updated mAP/AUC/d-prime numbers for Audio Set based on
changes of latest Audio Set revision. Changed wording to fit 4 page limit
with new addition
HopScotch - a low-power renewable energy base station network for rural broadband access
The provision of adequate broadband access to communities in sparsely populated rural areas has in the past been severely restricted. In this paper, we present a wireless broadband access test bed running in the Scottish Highlands and Islands which is based on a relay network of low-power base stations. Base stations are powered by a combination of renewable sources creating a low cost and scalable solution suitable for community ownership. The use of the 5~GHz bands allows the network to offer large data rates and the testing of ultra high frequency ``white space'' bands allow expansive coverage whilst reducing the number of base stations or required transmission power. We argue that the reliance on renewable power and the intelligent use of frequency bands makes this approach an economic green radio technology which can address the problem of rural broadband access
Mercury sources to Lake Ozette and Lake Dickey : highly contaminated remote coastal lakes, Washington State, USA
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Water, Air, & Soil Pollution 208 (2009): 275-286, doi:10.1007/s11270-009-0165-y.Mercury concentrations in largemouth bass and mercury accumulation rates in age-dated sediment cores were examined at Lake Ozette and Lake Dickey in Washington State. Goals of the study were to compare concentrations in fish tissues at the two lakes with lakes in a larger statewide dataset and evaluate factors influencing lake loading at Ozette and Dickey, which may include: catchment disturbances, coastal mercury cycling, and the role of trans-Pacific Asian mercury. Mercury fish tissue concentrations at the lakes were among the highest recorded in Washington State. Wet deposition and historical atmospheric monitoring from the area show no indication of enhanced deposition from Asian sources or coastal atmospheric processes. Sediment core records from the lakes displayed rapidly increasing sedimentation rates coinciding with commercial logging. The unusually high mercury flux rates and mercury tissue concentrations recorded at Lake Ozette and Lake Dickey appear to be associated with logging within the catchments
Epistatic Relationships between sarA and agr in Staphylococcus aureus Biofilm Formation
Background: The accessory gene regulator (agr) and staphylococcal accessory regulator (sarA) play opposing roles in Staphylococcus aureus biofilm formation. There is mounting evidence to suggest that these opposing roles are therapeutically relevant in that mutation of agr results in increased biofilm formation and decreased antibiotic susceptibility while mutation of sarA has the opposite effect. To the extent that induction of agr or inhibition of sarA could potentially be used to limit biofilm formation, this makes it important to understand the epistatic relationships between these two loci.
Methodology/Principal Findings: We generated isogenic sarA and agr mutants in clinical isolates of S. aureus and assessed the relative impact on biofilm formation. Mutation of agr resulted in an increased capacity to forma biofilmin the 8325-4 laboratory strain RN6390 but had little impact in clinical isolates S. aureus. In contrast, mutation of sarA resulted in a reduced capacity to form a biofilm in all clinical isolates irrespective of the functional status of agr. This suggests that the regulatory role of sarA in biofilm formation is independent of the interaction between sarA and agr and that sarA is epistatic to agr in this context. This was confirmed by demonstrating that restoration of sarA function restored the ability to form a biofilm even in the corresponding agr mutants. Mutation of sarA in clinical isolates also resulted in increased production of extracellular proteases and extracellular nucleases, both of which contributed to the biofilm-deficient phenotype of sarA mutants. However, studies comparing different strains with and without proteases inhibitors and/or mutation of the nuclease genes demonstrated that the agr-independent, sarA-mediated repression of extracellular proteases plays a primary role in this regard.
Conclusions and Significance: The results we report suggest that inhibitors of sarA-mediated regulation could be used to limit biofilm formation in S. aureus and that the efficacy of such inhibitors would not be limited by spontaneous mutation of agr in the human host
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Common genetic variants in the CLDN2 and PRSS1-PRSS2 loci alter risk for alcohol-related and sporadic pancreatitis
Pancreatitis is a complex, progressively destructive inflammatory disorder. Alcohol was long thought to be the primary causative agent, but genetic contributions have been of interest since the discovery that rare PRSS1, CFTR, and SPINK1 variants were associated with pancreatitis risk. We now report two significant genome-wide associations identified and replicated at PRSS1-PRSS2 (1×10-12) and x-linked CLDN2 (p < 1×10-21) through a two-stage genome-wide study (Stage 1, 676 cases and 4507 controls; Stage 2, 910 cases and 4170 controls). The PRSS1 variant affects susceptibility by altering expression of the primary trypsinogen gene. The CLDN2 risk allele is associated with atypical localization of claudin-2 in pancreatic acinar cells. The homozygous (or hemizygous male) CLDN2 genotype confers the greatest risk, and its alleles interact with alcohol consumption to amplify risk. These results could partially explain the high frequency of alcohol-related pancreatitis in men – male hemizygous frequency is 0.26, female homozygote is 0.07
The Multiplanet System TOI-421: A Warm Neptune and a Super Puffy Mini-Neptune Transiting a G9 V Star in a Visual Binary
We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations—comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echellé Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Échelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements—and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P_b = 5.19672 ± 0.00049 days, a mass of M_b = 7.17 ± 0.66 M⊕, and a radius of R_b = 2.68^(+0.19)_(-0.18) R⊕, whereas the outer warm Neptune, TOI-421 c, has a period of Pc = 16.06819 ± 0.00035 days, a mass of M_c = 16.42^(+1.06)_(-1.04) M⊕, a radius of R_c = 5.09^(+0.16)_(-0.15) R⊕ and a density of ρ_c = 0.685^(+0.080)_(-0.072) g cm⁻³. With its characteristics, the outer planet (ρ_c = 0.685^(+0.080)_(-0.072) g cm⁻³) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Lyα transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed
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