703 research outputs found
Renewable oxygenated additives in biofuels : high pressure densities of mixtures dibutyl-ether + heptane at high temperature and pressure
Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The increasing worldwide use of bio-fuels constitutes one of the measures considered to reduce greenhouse gas emissions. Bio-fuels also have an important part to play in promoting the security of energy supply, and promoting technological development and innovation. Di-butyl ether (DBE) is used as blending agent in reformulated gasoline and has been included in recent international regulations on the promotion of the use of energy from renewable sources for transport. The DBE is a non-polluting, high octane number blending agent. DBE could be also used as cetane enhancer in bio-diesel fuel, and can be obtained as an added valued additive to second generation bio-fuels. Second generation bio-fuels could be obtained from ligno-cellulosic biomass and waste materials.
Ether + alkane mixtures are of interest as model mixtures for gasoline in which the ether act as renewable, high octane number blending agent. From this point of view the study of the binary mixtures dibutyl ether + heptane, are very interesting. Heptane has been chosen as a representative of the linear alkanes that contain real gasoline. Density of the binary mixtures DBE + heptane and its pure compounds have been measured under pressure and reported in this work using a vibrating tube densitometer. Accurate PVT properties of pure ethers and its mixtures are required to develop and test equations of state, because equations of state are critical to design storage and transport systems in the fuel industry. Moreover, high temperature and pressure data serve to validate equations of state which are reliable for the increasingly use of industrial and engine processes under hard conditions.
Experimental densities (826 points) for the compressed liquid phase of the binary systems DBE + heptane have been measured at 298.15, 313.15, 333.15, 353.15, 373.15 and 393.15 K and at pressures up to 140 MPa, with an absolute uncertainty of 0.7 kg·m-3. For each composition, the experimental values were correlated using a Tait-type equation. Results show non-linear behaviour of the mixture.dc201
Experimental magnetic form factors in Co3V2O8: A combined study of ab initio calculations, magnetic Compton scattering and polarized neutron diffraction
We present a combination of ab initio calculations, magnetic Compton
scattering and polarized neutron experiments, which elucidate the density
distribution of unpaired electrons in the kagome staircase system Co3V2O8. Ab
initio wave functions were used to calculate the spin densities in real and
momentum space, which show good agreement with the respective experiments. It
has been found that the spin polarized orbitals are equally distributed between
the t2g and the eg levels for the spine (s) Co ions, while the eg orbitals of
the cross-tie (c) Co ions only represent 30% of the atomic spin density.
Furthermore, the results reveal that the magnetic moments of the cross-tie Co
ions, which are significantly smaller than those of the spine Co ions in the
zero-field ferromagnetic structure, do not saturate by applying an external
magnetic field of 2 T along the easy axis a, but that the increasing bulk
magnetization originates from induced magnetic moments on the O and V sites.
The refined individual magnetic moments are mu(Co_c)=1.54(4) mu_B,
mu(Co_s)=2.87(3) mu_B, mu(V)=0.41(4) mu_B, mu(O1)=0.05(5) mu_B, mu(O2)=0.35(5)
mu_B, and; mu(O3)=0.36(5) mu_B combining to the same macroscopic magnetization
value, which was previously only attributed to the Co ions
Diagnostic performance of serum pentraxin-3 in pediatric acute appendicitis: a prospective diagnostic validation study
Introduction
Pediatric acute appendicitis (PAA) is a pathology with a high rate of diagnostic error. The search for new diagnostic tools is justified by the high morbidity and healthcare costs associated with diagnostic error.
Methods
We designed a prospective study to validate serum pentraxin-3 (PTX3) as a diagnostic tool in PAA. Participants were divided into three groups: (1) patients with no underlying pathology (2) patients with non-surgical abdominal pain and (3) patients with a confirmed diagnosis of PAA. For further analyses, patients in group 3 were divided into complicated or uncomplicated PAA. Quantitative variables were expressed as medians and interquartile ranges and categorical variables as percentages. Quantitative variables were compared using the Kruskal–Wallis test and the Mann–Whitney U test. Diagnostic performance was evaluated with ROC curves.
Results
This study included 215 patients divided into group 1 (n : 63), group 2 (n : 53) and group 3 (n : 99). Median serum PTX3 values were 2.54 (1.70–2.95) ng/mL, 3.29 (2.19–7.64) ng/mL and 8.94 (6.16–14.05) in groups 1, 2 and 3, respectively (p : 0.001). Patients with complicated PAA showed significantly higher values than patients with uncomplicated PAA (p = 0.04). The AUC (group 2 vs. 3) was 0.77 (95/100 CI 0.69–0.85) and the best cut-off point was at 7.28 ng/mL, with a sensitivity of 61.3/100 and a specificity of 73.1/100. The AUC (complicated vs. uncomplicated PAA) was 0.65 (95/100 CI 0.54–0.77) and the best cut-off point was 12.33 ng/mL, with a sensitivity of 51.72/100 and a specificity of 72.73/100.
Conclusions
The diagnostic ability of serum PTX3 in PAA is only moderate and therefore it cannot be considered a definitive diagnostic test. The discriminatory ability of PTX3 between complicated and uncomplicated PAA is poor. These findings, which contrast with those reported to date, should be validated with future properly designed prospective studies
Hábitos, actitudes y conocimientos sobre la exposición solar de corredores de fondo en la Costa del Sol
A nivel dermatológico, la elevada exposición solar a radiación ultravioleta asociada a la práctica de actividades deportivas al aire libre, máxime en actividades recreativas de larga duración como son los corredores de fondo, aumenta el fotoenvejecimiento de la piel y la incidencia de cáncer de piel. El propósito del estudio fue evaluar los hábitos, actitudes y conocimientos sobre la exposición solar de corredores de fondo de nuestra comunidad. Se realizó un estudio transversal descriptivo mediante encuesta con un muestreo de conveniencia entre aquellos participantes de las medias maratones populares de Fuengirola y Marbella celebradas en el mes de septiembre del año 2016. En la muestra evaluada se ha hallado una intensa exposición solar realizando actividades al aire libre, asociado ello a una prevalencia de quemaduras solares elevada (uno de cada 2 corredores).
Exposure to UV radiation during the practice of sports in the open air is especially high in sustained recreational activities such as long-distance running. UV exposure increases skin photoaging and the incidence of skin cancer. This study aimed to describe habits and attitudes related to sun exposure among long-distance runners in our area of southern Spain as well as to evaluate the runners’ knowledge of exposure. A cross-sectional descriptive study was designed to survey a convenience sample of participants in half marathons in Fuengirola and Marbella in September 2016. We found a high level of sun exposure among participants in this outdoor activity. The prevalence of sunburn was also high, experienced by half of the runners surveyed
A Mediterranean lifestyle reduces the risk of cardiovascular disease in the “Seguimiento Universidad de Navarra” (SUN) cohort
Background and aims: A healthy lifestyle is essential to prevent cardiovascular disease
(CVD). However, beyond dietary habits, there is a scarcity of studies comprehensively assessing
the typical traditional Mediterranean lifestyle with a multi-dimensional index. We assessed the
association between the Mediterranean lifestyle (measured with the MEDLIFE index including
diet, physical activity, and other lifestyle factors) and the incidence of CVD.
Methods and results: The “Seguimiento Universidad de Navarra” (SUN) project is a prospective,
dynamic and multipurpose cohort of Spanish university graduates. We calculated a MEDLIFE
score, composed of 28 items on food consumption, dietary habits, physical activity, rest, social
habits, and conviviality, for 18,631 participants by assigning 1 point for each typical Mediterra-
nean lifestyle factor achieved, for a theoretically possible final score ranging from 0 to 28 points.
During an average follow-up of 11.5 years, 172 CVD cases (myocardial infarction, stroke or cardio-
vascular death) were observed. An inverse association between the MEDLIFE score and the risk of
primary cardiovascular events was observed, with multivariable-adjusted hazard ratio
(HR) Z 0.50; (95% confidence interval, 0.31e0.81) for the highest MEDLIFE scores (14e23 points)
compared to the lowest scores (0e9 points), p (trend) Z 0.004.
Conclusion: A higher level of adherence to the Mediterranean lifestyle was significantly associ-
ated with a lower risk of CVD in a Spanish cohort. Public health strategies should promote the
Mediterranean lifestyle to preserve cardiovascular health
The ALHAMBRA survey : band luminosity function of quiescent and star-forming galaxies at by PDF analysis
Our goal is to study the evolution of the band luminosity function (LF)
since using ALHAMBRA data. We used the photometric redshift and the
band selection magnitude probability distribution functions (PDFs) of those
ALHAMBRA galaxies with mag to compute the posterior LF. We
statistically studied quiescent and star-forming galaxies using the template
information encoded in the PDFs. The LF covariance matrix in
redshift-magnitude-galaxy type space was computed, including the cosmic
variance. That was estimated from the intrinsic dispersion of the LF
measurements in the 48 ALHAMBRA sub-fields. The uncertainty due to the
photometric redshift prior is also included in our analysis. We modelled the LF
with a redshift-dependent Schechter function affected by the same selection
effects than the data. The measured ALHAMBRA LF at and the
evolving Schechter parameters both for quiescent and star-forming galaxies
agree with previous results in the literature. The estimated redshift evolution
of is and , and of is
and . The measured faint-end slopes are and . We find a significant
population of faint quiescent galaxies, modelled by a second Schechter function
with slope . We find a factor decrease in the
luminosity density of star-forming galaxies, and a factor
increase in the of quiescent ones since , confirming the continuous
build-up of the quiescent population with cosmic time. The contribution of the
faint quiescent population to increases from 3% at to 6% at .
The developed methodology will be applied to future multi-filter surveys such
as J-PAS.Comment: Accepted for publication in Astronomy and Astrophysics. 25 pages, 20
figures, 7 table
Oral Anticoagulation and Risk of Symptomatic Hemorrhagic Transformation in Stroke Patients Treated With Mechanical Thrombectomy: Data From the Nordictus Registry
Introduction: We aimed to evaluate if prior oral anticoagulation (OAC) and its type determines a greater risk of symptomatic hemorrhagic transformation in patients with acute ischemic stroke (AIS) subjected to mechanical thrombectomy. Materials and
Methods: Consecutive patients with AIS included in the prospective reperfusion registry NORDICTUS, a network of tertiary stroke centers in Northern Spain, from January 2017 to December 2019 were included. Prior use of oral anticoagulants, baseline variables, and international normalized ratio (INR) on admission were recorded. Symptomatic intracranial hemorrhage (sICH) was the primary outcome measure. Secondary outcome was the relation between INR and sICH, and we evaluated mortality and functional outcome at 3 months by modified Rankin scale. We compared patients with and without previous OAC and also considered the type of oral anticoagulants.
Results: About 1.455 AIS patients were included, of whom 274 (19%) were on OAC, 193 (70%) on vitamin K antagonists (VKA), and 81 (30%) on direct oral anticoagulants (DOACs). Anticoagulated patients were older and had more comorbidities. Eighty-one (5.6%) developed sICH, which was more frequent in the VKA group, but not in DOAC group. OAC with VKA emerged as a predictor of sICH in a multivariate regression model (OR, 1.89 [95% CI, 1.01–3.51], p = 0.04) and was not related to INR level on admission. Prior VKA use was not associated with worse outcome in the multivariate regression model nor with mortality at 3 months.
Conclusions: OAC with VKA, but not with DOACs, was an independent predictor of sICH after mechanical thrombectomy. This excess risk was associated neither with INR value by the time thrombectomy was performed, nor with a worse functional outcome or mortality at 3 months
J-NEP: 60-band photometry and photometric redshifts for the James Webb Space Telescope North Ecliptic Pole Time-Domain Field
The J-PAS survey will observe ~1/3 of the northern sky with a set of 56
narrow-band filters using the dedicated 2.55 m JST telescope at the Javalambre
Astrophysical Observatory. Prior to the installation of the main camera, in
order to demonstrate the scientific potential of J-PAS, two small surveys were
performed with the single-CCD Pathfinder camera: miniJPAS (~1 deg2 along the
Extended Groth Strip), and J-NEP (~0.3 deg2 around the JWST North Ecliptic Pole
Time Domain Field), including all 56 J-PAS filters as well as u, g, r, and i.
J-NEP is ~0.5-1.0 magnitudes deeper than miniJPAS, providing photometry for
24,618 r-band detected sources and photometric redshifts (photo-z) for the
6,662 sources with r<23.
In this paper we describe the photometry and photo-z of J-NEP and demonstrate
a new method for the removal of systematic offsets in the photometry based on
the median colours of galaxies, dubbed "galaxy locus recalibration". This
method does not require spectroscopic observations except in a few reference
pointings and, unlike previous methods, is applicable to the whole J-PAS
survey.
We use a spectroscopic sample of 787 galaxies to test the photo-z performance
for J-NEP and in comparison to miniJPAS. We find that the deeper J-NEP
observations result in a factor ~1.5-2 decrease in sigma_NMAD (a robust
estimate of the standard deviation of the photo-z error) and the outlier rate
relative to miniJPAS for r>21.5 sources, but no improvement in brighter ones.
We find the same relation between sigma_NMAD and odds in J-NEP and miniJPAS,
suggesting sigma_NMAD can be predicted for any set of J-PAS sources from their
odds distribution alone, with no need for additional spectroscopy to calibrate
the relation. We explore the causes for photo-z outliers and find that
colour-space degeneracy at low S/N, photometry artifacts, source blending, and
exotic spectra are the most important factors.Comment: 16 pages, 25 figures, accepted for publication in Astronomy and
Astrophysic
Quinine doped hybrid sol-gel coatings for wave guiding and optical applications
Pure and quinine doped silica coatings have been prepared over sodalime glasses. The coatings were consolidated at low temperature (range 60-180 A degrees C) preserving optical activity of quinine molecule. We designed a device to test the guiding properties of the coatings. We confirmed with this device that light injected in pure silica coatings is guided over distances of meters while quinine presence induces isotropic photoluminescence. With the combined use of both type of coatings, it is possible to design light guiding devices and illuminate regions in glass elements without electronic circuits
The effect of early treatment with ivermectin on viral load, symptoms and humoral response in patients with non-severe COVID-19: A pilot, double-blind, placebo-controlled, randomized clinical trial.
Background
Ivermectin inhibits the replication of SARS-CoV-2 in vitro at concentrations not readily achievable with currently approved doses. There is limited evidence to support its clinical use in COVID-19 patients. We conducted a Pilot, randomized, double-blind, placebo-controlled trial to evaluate the efficacy of a single dose of ivermectin reduce the transmission of SARS-CoV-2 when administered early after disease onset.
Methods
Consecutive patients with non-severe COVID-19 and no risk factors for complicated disease attending the emergency room of the Clínica Universidad de Navarra between July 31, 2020 and September 11, 2020 were enrolled. All enrollments occurred within 72 h of onset of fever or cough. Patients were randomized 1:1 to receive ivermectin, 400 mcg/kg, single dose (n = 12) or placebo (n = 12). The primary outcome measure was the proportion of patients with detectable SARS-CoV-2 RNA by PCR from nasopharyngeal swab at day 7 post-treatment. The primary outcome was supported by determination of the viral load and infectivity of each sample. The differences between ivermectin and placebo were calculated using Fisher's exact test and presented as a relative risk ratio. This study is registered at ClinicalTrials.gov: NCT04390022.
Findings
All patients recruited completed the trial (median age, 26 [IQR 19-36 in the ivermectin and 21-44 in the controls] years; 12 [50%] women; 100% had symptoms at recruitment, 70% reported headache, 62% reported fever, 50% reported general malaise and 25% reported cough). At day 7, there was no difference in the proportion of PCR positive patients (RR 0·92, 95% CI: 0·77-1·09, p = 1·0). The ivermectin group had non-statistically significant lower viral loads at day 4 (p = 0·24 for gene E; p = 0·18 for gene N) and day 7 (p = 0·16 for gene E; p = 0·18 for gene N) post treatment as well as lower IgG titers at day 21 post treatment (p = 0·24). Patients in the ivermectin group recovered earlier from hyposmia/anosmia (76 vs 158 patient-days; p < 0.001).
Interpretation
Among patients with non-severe COVID-19 and no risk factors for severe disease receiving a single 400 mcg/kg dose of ivermectin within 72 h of fever or cough onset there was no difference in the proportion of PCR positives. There was however a marked reduction of self-reported anosmia/hyposmia, a reduction of cough and a tendency to lower viral loads and lower IgG titers which warrants assessment in larger trials.
Funding
ISGlobal, Barcelona Institute for Global Health and Clínica Universidad de Navarra
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