388 research outputs found
The impact of fuel properties on the emissions from the combustion of biomass and other solid fuels in a fixed bed domestic stove
Experimental results are presented on the emissions from a single combustion chamber stove burning wood, coal and processed fuels. This technique was used to permit comparisons to be made of the influence of different fuel types without it being influenced by the effects of secondary combustion. Measurements were made of CO, NOx and fine particulates during the major phases of combustion, namely flaming and smouldering. Measurements of the particulates were made in two ways: firstly using a gravimetric total particulate measurement and secondly using a cyclone technique to give PM2.5 and PM10 size fractions. Smoke emissions from the different fuels were very dependent on the phase of combustion especially for the total particulate results, where flaming phase emissions were much higher than in the smouldering phase. It was found that the particulate emission factors for the wood fuels were dependent on the volatile content whilst the coals followed a different pattern. NOx was linearly dependent on the fuel-N content for all the fuel types, but the relationship for biomass is different from that for coal. CO emissions were very dependent on the combustion phase
Predictors of Cervical Cancer Screening among Infrequently Screened Women Completing Human Papillomavirus Self-Collection: My Body My Test-1
Background: Approximately one-half of cervical cancer cases in the United States occur in underscreened or never-screened women. We examined predictors to completing Papanicolaou (Pap) testing and whether a positive human papillomavirus (HPV) self-collection result affects Pap testing adherence among underscreened women. Materials and Methods: Low-income women aged 30-65 years who reported no Pap testing in ≥4 years were recruited in North Carolina. Knowledge, attitudes, and barriers regarding cervical cancer and Pap testing were assessed by telephone questionnaires. We mailed self-collection kits for HPV testing and provided information regarding where to obtain affordable Pap testing. Participants received $45 for completing all activities. We used multivariable logistic regression to assess the predictors of longer reported time since last Pap (≥10 vs. 4-9 years) and of completion of Pap testing following study enrollment (follow-up Pap). Results: Participants (n = 230) were primarily black (55%), uninsured (64%), and with ≤high school education (59%). Cost and finding an affordable clinic were the most commonly reported barriers to screening. White women and those with ≤high school education reported longer intervals since last Pap test. Half of the participants reported completing a follow-up Pap test (55%). Women with a positive HPV self-collection were five times more likely to report completing a follow-up Pap test than those with negative self-collection (odds ratio = 5.1, 95% confidence interval 1.4-25.7). Conclusions: Improving awareness of resources for affordable screening could increase cervical cancer screening in underserved women. Home-based HPV self-collection represents an opportunity to re-engage infrequently screened women into preventive screening services
A study of smoke formation from wood combustion
Aerosol time of flight mass spectrometry (ATOFMS) was used to analyse the particles emitted during the flaming and smouldering phases of the combustion of samples of hard and soft woods. Eugenol and furfural were also burned and using results from previous work of the authors, they have been shown to be useful proxies for initial wood combustion products. The ratios of elementary carbon to total carbon in the particles were similar for both the woods and for eugenol. The ATOFMS spectra of most of the particles were consistent with the presence of soot precursor constituents along with oxygen containing fragments. Most particle diameters were less than 2.5. μm, with the greatest concentration of <. 0.12. μm
Combustion and pyrolysis reactions of alkylated polycyclic aromatic compounds: The decomposition of 13C methylarenes in relation to diesel engine emissions
The thermal decomposition of methylarenes labelled with 13C in the methyl group was investigated. This was conducted using both a direct injection diesel engine and a pyrolysis flow cell connected to a GC-MS. 2-[13C]methylnaphthalene and 9-[13C]methylphenanthrene were synthesized by means of the Corey-House coupling reaction and their identity and purity confirmed by mass spectrometry and NMR. GC-MS analysis of the aromatic fraction separated from the extract of the exhaust particulate collected from the engine operated with n-hexadecane doped with the labelled methylnaphthalene showed that the 13C was not redistributed among the methyl groups of higher PAH. However, with 9-[13C]methylphenanthrene in the fuel a significant amount was retained in the particulate, even though the principal in-cylinder reaction was dealkylation. Pyrolytic reactions of the 13C-labelled methyl arenes were studied in a micro-pyrolysis-GC-MS-apparatus and confirmed dealkylation as the predominant reaction. The detailed chemical mechanism of the pyrolysis was explained by a scheme involving two alternative radical transfer reactions
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
Particle-yield modification in jet-like azimuthal di-hadron correlations in Pb-Pb collisions at = 2.76 TeV
The yield of charged particles associated with high- trigger
particles ( GeV/) is measured with the ALICE detector in
Pb-Pb collisions at = 2.76 TeV relative to proton-proton
collisions at the same energy. The conditional per-trigger yields are extracted
from the narrow jet-like correlation peaks in azimuthal di-hadron correlations.
In the 5% most central collisions, we observe that the yield of associated
charged particles with transverse momenta GeV/ on the
away-side drops to about 60% of that observed in pp collisions, while on the
near-side a moderate enhancement of 20-30% is found.Comment: 15 pages, 2 captioned figures, 1 table, authors from page 10,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/350
PAH emissions from an African cookstove
Combustion of wood and other biomass is a significant contributor to poor air quality in many developing countries. Emissions of particulates and Polycyclic Aromatic Hydrocarbons (PAH) are a major health hazard, particularly in Africa where the use of domestic cookstoves has increased alongside population expansion. Because of economic factors firewood is commonly used in place of the more expensive charcoal; particularly in rural areas. This work conducts a study of PAH emissions from an African cookstove comparing the combustion of both charcoal and firewood. It is demonstrated that PAH and particulate emissions are much higher from the firewood compared to the charcoal. The difference in levels can be interpreted due to the importance of the pyrolysis reactions of the volatile components of wood in PAH formation, whereas these volatiles emissions are much smaller from charcoal. Analysis of the combustion phases (flaming, smouldering) is undertaken and a computer model has been developed to link the composition of the fuels to the emissions of the PAH and particulates. The modelled PAH levels are shown to follow a similar trend to the experimental results
Erros inatos do metabolismo confirmados no Hospital das Clínicas de Ribeirão Preto-SP no período de 2000 a 2008
Os Erros Inatos do Metabolismo (EIM) vêm sendo cada vez mais identificados nos últimos anos. A preocupação com o diagnóstico precoce decorre do foco na prevenção de deficiências, especialmente a mental. Este estudo descritivo teve por objetivo verificar diagnósticos confirmados e modalidades de tratamento utilizadas de janeiro de 2000 a dezembro de 2008. Método: foi realizada busca ativa de casos confirmados nos serviços que atendem esse tipo doença: neurologia (neuropediatria e doenças neuromusculares), pediatria (serviço de gastrologia e hepatologia) e genética clínica, além de levantamento no Serviço de Arquivo Médico do HCFMRP-USP. Foram confirmados 165 pacientes com EIM, com idades de um dia a 22 anos (mediana de um ano); 50 casos foram defeitos na síntese ou catabolismo de moléculas complexas, 65 no metabolismo intermediário, e 50 na produção ou utilização de energia. O tratamento foi instituído para 12 dos 50 pacientes do grupo I sendo reposição enzimática em 11 e transplante de medula óssea em um; todos do grupo II e III receberam orientação nutricional; 60 do grupo II receberam fórmula dietética industrializada; dos 50 do grupo III, 43 com mitocondriopatias receberam L-carnitina e coenzimas e aqueles com glicogenose, orientação sobre aporte de carbohidratos. A formação de novos recursos humanos, integração com a Rede EIM Brasil e linhas de pesquisa na área são prioridades para melhorar a acuidade na detecção e tratamento de erros inatos do metabolismo.Inborn Errors of Metabolism have been increasingly identified in recent years. The early diagnosis focuses on prevention of disabilities, especially mental retardation. This descriptive study aims to verify confirmed diagnosis and treatment modalities in HCFMRP-USP cases from January of 2000 to December of 2008. A total of 165 patients with ages ranging from one day to 22 years (median one year) were detected. Fifty patients had synthesis or catabolism of complex molecules (group I), 65 intermediary metabolism (group II), and 50 had production or use of energy (group III) defects. Among the patients of group I, 11 had enzyme replacement therapy, and one bone marrow transplantation; for group II and III, in addition to daily nutritional guidance for all of the patients, 60 from group II received industrialized diets; from group III, 43 with mitochondrial diseases received L-carnitine and coenzymes, and those with glycogenosis were focused mainly on the intake of carbohydrates. New human resources, integration with the Network EIM Brazil and lines of research in the area are priorities for improving the accuracy in the detection and treatment of inborn errors of metabolism
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