77 research outputs found
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MINIMIZING NET CO2 EMISSIONS BY OXIDATIVE CO-PYROLYSIS OF COAL / BIOMASS BLENDS
This study presents a set of thermodynamic calculations on the optimal mode of solid fuel utilization considering a wide range of fuel types and processing technologies. The technologies include stand-alone combustion, biomass/coal cofiring, oxidative pyrolysis, and straight carbonization with no energy recovery but with elemental carbon storage. The results show that the thermodynamically optimal way to process solid fuels depends strongly on the specific fuels and technologies available, the local demand for heat or for electricity, and the local baseline energy-production method. Burning renewable fuels reduces anthropogenic CO{sub 2} emissions as widely recognized. In certain cases, however, other processing methods are equally or more effective, including the simple carbonization or oxidative pyrolysis of biomass fuels
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MINIMIZING NET CARBON DIOXIDE EMISSIONS BY OXIDATIVE CO-PYROLYSIS OF COAL/BIOMASS BLENDS
Solid fuels vary significantly with respect to the amount of CO{sub 2} directly produced per unit heating value. Elemental carbon is notably worse than other solid fuels in this regard, and since carbon (char) is an intermediate product of the combustion of almost all solid fuels, there is an opportunity to reduce specific CO{sub 2} emissions by reconfiguring processes to avoid char combustion wholly or in part. The primary goal of this one-year Innovative Concepts project is to make a fundamental thermodynamic assessment of three modes of solid fuel use: (1) combustion, (2) carbonization, and (3) oxidative pyrolysis, for a wide range of coal and alternative solid fuels. This period a large set of thermodynamic calculations were carried out to assess the potential of the three processes. The results show that the net carbon dioxide emissions and the relative ranking of the different processes depends greatly on the particular baseline fossil fuel being displaced by the new technology. As an example, in a baseline natural gas environment, it is thermodynamically more advantageous to carbonize biomass than to combust it, and even more advantageous to oxidatively pyrolyze the biomass
UV Imaging Polarimetry of the peculiar Seyfert 2 galaxy Mrk 477
We present the results of UV imaging polarimetry of the Seyfert 2 galaxy Mrk
477 taken by the Faint Object Camera onboard the Hubble Space Telescope (HST).
From a previous HST UV image (lambda ~ 2180A), Mrk 477 has been known to have
a pointlike bright UV hotspot in the central region, peculiar among nearby
Seyfert 2 galaxies. There are also claims of UV/optical variability, unusual
for a Seyfert 2 galaxy. Our data show that there is an off-nuclear scattering
region ~ 0."6 (~ 500 pc) NE from the hotspot. The data, after the subtraction
of the instrumental effect due to this bright hotspot region, might indicate
that the scattered light is also detected in the central 0."2 radius region and
is extended to a very wide angle. The hotspot location is consistent with the
symmetry center of the PA pattern, which represents the location of the hidden
nucleus, but our data do not provide a strong upper limit to the distance
between the symmetry center and the hotspot. We have obtained high spatial
resolution color map of the continuum which shows that the nuclear spiral arm
of 0."4 scale (~ 300pc) is significantly bluer than the off-nuclear mirror and
the hotspot region. The nature of the hotspot is briefly discussed.Comment: To appear in Ap
UV Imaging Polarimetry of the Seyfert 2 Galaxy Mrk 3
We present UV imaging polarimetry data of the Seyfert 2 galaxy Mrk 3 taken by
the Hubble Space Telescope. The polarized flux is found to be extended to ~1
kpc from the nucleus, and the position angles of polarization are
centrosymmetric, confirming that the polarization is caused by scattering. We
determine the location of the hidden nucleus as the center of this
centrosymmetric pattern. From the polarization images taken in two broad bands,
we have obtained the color distribution of the polarized flux. Some regions
have blue polarized flux, consistent with optically-thin dust scattering, but
some bright knots have a color similar to that of Seyfert 1 nucleus. Also, the
recent Chandra X-ray observation suggests that the ratio of scattered UV flux
to scattered X-ray flux is rather similar to the intrinsic UV/X-ray ratio in a
Seyfert 1 nucleus, if the observed extended X-ray continuum is scattered light.
While the scattered X-ray would be essentially from electron scattering, the UV
slope and UV/X-ray ratio both being similar to Seyfert 1's would lead to two
possibilities as to the nature of the UV scatterers. One is that the UV may
also be scattered by electrons, in which case the scattering gas is somehow
dust-free. The other is that the UV is scattered by dust grains, but the
wavelength-independent UV scattering with low efficiency indicated by the UV
slope and UV/X-ray ratio would suggest that the grains reside in UV-opaque
clouds, or the dust might be mainly composed of large grains and lacks
small-grain population.Comment: 15 pages, 8 figures (plus 2 color versions of grayscale figures), To
appear in ApJ; minor corrections for the proofs of the manuscrip
UV Spectropolarimetry of Narrow-line Radio Galaxies
We present the results of UV spectropolarimetry (2000 - 3000A) and far-UV
spectroscopy (1500 - 2000A) of two low-redshift narrow-line radio galaxies
(NLRGs) taken with the Faint Object Spectrograph onboard the Hubble Space
Telescope (HST). Spectropolarimetry of several NLRGs has shown that, by the
presence of broad permitted lines in polarized flux spectrum, they have hidden
quasars seen through scattered light. Imaging polarimetry has shown that NLRGs
including our targets often have large scattering regions of a few kpc to >~10
kpc scale. This has posed a problem about the nature of the scatterers in these
radio galaxies. Their polarized continuum has the spectral index similar to or
no bluer than that of quasars, which favors electrons as the dominant
scattering particles. The large scattering region size, however, favors dust
scattering, because of its higher scattering efficiency compared to electrons.
In this paper, we investigate the polarized flux spectrum over a wide
wavelength range, combining our UV data with previous optical/infrared
polarimetry data. We infer that the scattering would be often caused by opaque
dust clouds in the NLRGs and this would be a part of the reason for the
apparently grey scattering. In the high-redshift radio galaxies, these opaque
clouds could be the proto-galactic subunits inferred to be seen in the HST
images. However, we still cannot rule out the possibility of electron
scattering, which could imply the existence of a large gas mass surrounding
these radio galaxies.Comment: 25 pages, 21 figures. To appear in Ap
ELCID: early lung cancer identification and diagnosis - an embedded interview study to explore patient participation and recruitment
Background
The ELCID Trial is a feasibility randomised controlled
trial examining the effect on lung cancer diagnosis of
giving an urgent chest x-ray to smokers, and recent exsmokers,
aged over 60 with new chest symptoms.
Aims
The qualitative component explores the feasibility of
individually randomising patients to an urgent CXR or
not and investigates any barriers to patient participation.
Methods
To date we have conducted semi-structured interviews
with six primary care staff (practice managers, research
nurses), ten patients randomised to âextra-NICEâ guidelines
for referral for urgent chest x-ray, and six patients
randomised to âusual careâ (NICE guidelines)). We hope
to also interview patients who decline randomisation.
Interviews were analysed using a Framework approach.
Results
Initial analysis indicated that practices have struggled to
recruit patients, partly due to the eligibility criteria that
requires ex-smokers to have stopped smoking within the
last five years. Practices with a research nurse have
recruited the most patients. Patients indicated that they
are happy to take part in the trial and their anxiety
levels were not raised. Most patients hoped to be
randomised to urgent chest x-ray, although those who
were not did not go back to their GP to request one.
Conclusions
Eligibility criteria needed revision to include ex-smokers
of any duration. These preliminary findings suggest that
the trial appears to be feasible and patients are happy to
accept randomisation. The findings will inform the
design of the main trial in the future
Estimating Sensitivity of Laboratory Testing for Influenza in Canada through Modelling
Background: The weekly proportion of laboratory tests that are positive for influenza is used in public health surveillance systems to identify periods of influenza activity. We aimed to estimate the sensitivity of influenza testing in Canada based on results of a national respiratory virus surveillance system. Methods and Findings: The weekly number of influenza-negative tests from 1999 to 2006 was modelled as a function of laboratory-confirmed positive tests for influenza, respiratory syncytial virus (RSV), adenovirus and parainfluenza viruses, seasonality, and trend using Poisson regression. Sensitivity was calculated as the number of influenza positive tests divided by the number of influenza positive tests plus the model-estimated number of false negative tests. The sensitivity of influenza testing was estimated to be 33 % (95%CI 32â34%), varying from 30â40 % depending on the season and region. Conclusions: The estimated sensitivity of influenza tests reported to this national laboratory surveillance system is considerably less than reported test characteristics for most laboratory tests. A number of factors may explain this difference, including sample quality and specimen procurement issues as well as test characteristics. Improved diagnosis would permit better estimation of the burden of influenza
Genomic mining of prokaryotic repressors for orthogonal logic gates
Genetic circuits perform computational operations based on interactions between freely diffusing molecules within a cell. When transcription factors are combined to build a circuit, unintended interactions can disrupt its function. Here, we apply 'part mining' to build a library of 73 TetR-family repressors gleaned from prokaryotic genomes. The operators of a subset were determined using an in vitro method, and this information was used to build synthetic promoters. The promoters and repressors were screened for cross-reactions. Of these, 16 were identified that both strongly repress their cognate promoter (5- to 207-fold) and exhibit minimal interactions with other promoters. Each repressor-promoter pair was converted to a NOT gate and characterized. Used as a set of 16 NOT/NOR gates, there are >10[superscript 54] circuits that could be built by changing the pattern of input and output promoters. This represents a large set of compatible gates that can be used to construct user-defined circuits.United States. Air Force Office of Scientific Research (Award FA9550-11-C-0028)American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowship (32 CFR 168a)United States. Defense Advanced Research Projects Agency. Chronical of Lineage Indicative of Origins (N66001-12-C-4016)United States. Office of Naval Research (N00014-13-1-0074)National Institutes of Health (U.S.) (GM095765)National Science Foundation (U.S.). Synthetic Biology Engineering Research Center (SA5284-11210
Protective efficacy of interventions for preventing malaria mortality in children in Plasmodium falciparum endemic areas
Background Insecticide-treated mosquito nets (ITNs) and indoor-residual spraying (IRS) are recommended strategies for preventing malaria in children. While their impact on all-cause child mortality is well documented, their impact on reducing malaria-attributable mortality has not been quantified. While the impact of intermittent preventive therapy in pregnant women (IPTp) and ITNs in pregnancy for improving birth outcomes is also well established, their impact on preventing neonatal or child mortality has not been quantified
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