63 research outputs found
Comparative evaluation of R1234yf, R1234ze(E) and R450A as alternatives to R134a in a variable speed reciprocating compressor
A comparative energetic evaluation of R1234yf, R1234ze(E) and R450A as alternatives to R134a in a
variable speed compressor is carried out. A compressor model based on dimensionless numbers was
obtained using the Buckingham
p
-theorem, which was validated with experimental data; showing that
the prediction error of the model is lower than
±
10% and
±
2 K for temperature. The experimental data
were obtained by testing R134a, R1234yf, R1234ze(E) and R450A for a wide range of operating condi-
tions. Results obtained with the validated model, show that the dimensionless approach provides a
similar estimation of energy parameters compared with the experimental results, such as power con-
sumption, refrigerant mass
fl
ow rate, cooling capacity, COP, discharge temperature and compressor ef-
fi
ciencies for each refrigerant tested using the dimensionless approach proposed. The comparative
evaluation of the compressor predictions shows a reduction in the cooling capacity obtained with
R1234yf, R450A and R1234ze(E), in comparison with R134a. Also, COP values for R1234yf, R450A, and
R1234ze(E) are lower than those obtained from R134a. Finally, results shows that the dimensionless
correlation compressor model can be used to predict the performance of other reciprocating compres-
sors, at similar operating conditions for a wide range of compressor rotation speed, with a reasonable
accuracy.The authors thankfully acknowledge to the "Consejo Nacional deCiencia y Tecnología (CONACYT)” for their support to this study, and to the “Ministerio de Educación, Cultura y Deporte” (Grant number FPU12/02841) for sponsoring this work through
“Becas y Contratosde Formación de Profesorado Universitario del Programa Nacional
de Formación de Recursos Humanos de Investigación del ejercicio
2012”
SHINING, A Survey of Far-infrared Lines in Nearby Galaxies. I. Survey Description, Observational Trends, and Line Diagnostics
We use the Herschel/PACS spectrometer to study the global and spatially resolved far-infrared (FIR) fine-structure line emission in a sample of 52 galaxies that constitute the SHINING survey. These galaxies include star-forming, active-galactic nuclei (AGN), and luminous infrared galaxies (LIRGs). We find an increasing number of galaxies (and kiloparsec size regions within galaxies) with low line-to-FIR continuum ratios as a function of increasing FIR luminosity (), dust infrared color, to molecular gas mass ratio (), and FIR surface brightness (). The correlations between the [CII]/FIR or [OI]/FIR ratios with are remarkably tight ( dex scatter over almost four orders of magnitude in ). We observe that galaxies with and kpc tend to have weak fine-structure line-to-FIR continuum ratios, and that LIRGs with infrared sizes kpc have line-to-FIR ratios comparable to those observed in typical star-forming galaxies. We analyze the physical mechanisms driving these trends in Paper II (Herrera-Camus et al. 2018). The combined analysis of the [CII], [NII], and [OIII] lines reveals that the fraction of the [CII] line emission that arises from neutral gas increases from 60% to 90% in the most active star-forming regions and that the emission originating in the ionized gas is associated with low-ionization, diffuse gas rather than with dense gas in HII regions. Finally, we report the global and spatially resolved line fluxes of the SHINING galaxies to enable the comparison and planning of future local and high- studies
Euclid Preparation. XXVIII. Forecasts for ten different higher-order weak lensing statistics
Recent cosmic shear studies have shown that higher-order statistics (HOS)
developed by independent teams now outperform standard two-point estimators in
terms of statistical precision thanks to their sensitivity to the non-Gaussian
features of large-scale structure. The aim of the Higher-Order Weak Lensing
Statistics (HOWLS) project is to assess, compare, and combine the constraining
power of ten different HOS on a common set of -like mocks, derived from
N-body simulations. In this first paper of the HOWLS series, we computed the
nontomographic (, ) Fisher information for the
one-point probability distribution function, peak counts, Minkowski
functionals, Betti numbers, persistent homology Betti numbers and heatmap, and
scattering transform coefficients, and we compare them to the shear and
convergence two-point correlation functions in the absence of any systematic
bias. We also include forecasts for three implementations of higher-order
moments, but these cannot be robustly interpreted as the Gaussian likelihood
assumption breaks down for these statistics. Taken individually, we find that
each HOS outperforms the two-point statistics by a factor of around two in the
precision of the forecasts with some variations across statistics and
cosmological parameters. When combining all the HOS, this increases to a
times improvement, highlighting the immense potential of HOS for cosmic shear
cosmological analyses with . The data used in this analysis are
publicly released with the paper.Comment: 33 pages, 24 figures, main results in Fig. 19 & Table 5, version
published in A&
Euclid preparation. XXXI. The effect of the variations in photometric passbands on photometric-redshift accuracy
The technique of photometric redshifts has become essential for the
exploitation of multi-band extragalactic surveys. While the requirements on
photo-zs for the study of galaxy evolution mostly pertain to the precision and
to the fraction of outliers, the most stringent requirement in their use in
cosmology is on the accuracy, with a level of bias at the sub-percent level for
the Euclid cosmology mission. A separate, and challenging, calibration process
is needed to control the bias at this level of accuracy. The bias in photo-zs
has several distinct origins that may not always be easily overcome. We
identify here one source of bias linked to the spatial or time variability of
the passbands used to determine the photometric colours of galaxies. We first
quantified the effect as observed on several well-known photometric cameras,
and found in particular that, due to the properties of optical filters, the
redshifts of off-axis sources are usually overestimated. We show using simple
simulations that the detailed and complex changes in the shape can be mostly
ignored and that it is sufficient to know the mean wavelength of the passbands
of each photometric observation to correct almost exactly for this bias; the
key point is that this mean wavelength is independent of the spectral energy
distribution of the source}. We use this property to propose a correction that
can be computationally efficiently implemented in some photo-z algorithms, in
particular template-fitting. We verified that our algorithm, implemented in the
new photo-z code Phosphoros, can effectively reduce the bias in photo-zs on
real data using the CFHTLS T007 survey, with an average measured bias Delta z
over the redshift range 0.4<z<0.7 decreasing by about 0.02, specifically from
Delta z~0.04 to Delta z~0.02 around z=0.5. Our algorithm is also able to
produce corrected photometry for other applications.Comment: 19 pages, 13 figures; Accepted for publication in A&
Euclid preparation XXVIII. Forecasts for ten different higher-order weak lensing statistics
Recent cosmic shear studies have shown that higher-order statistics (HOS) developed by independent teams now outperform standard two-point estimators in terms of statistical precision thanks to their sensitivity to the non-Gaussian features of large-scale structure. The aim of the Higher-Order Weak Lensing Statistics (HOWLS) project is to assess, compare, and combine the constraining power of ten different HOS on a common set of Euclid-like mocks, derived from N-body simulations. In this first paper of the HOWLS series, we computed the nontomographic (Ωm, σ8) Fisher information for the one-point probability distribution function, peak counts, Minkowski functionals, Betti numbers, persistent homology Betti numbers and heatmap, and scattering transform coefficients, and we compare them to the shear and convergence two-point correlation functions in the absence of any systematic bias. We also include forecasts for three implementations of higher-order moments, but these cannot be robustly interpreted as the Gaussian likelihood assumption breaks down for these statistics. Taken individually, we find that each HOS outperforms the two-point statistics by a factor of around two in the precision of the forecasts with some variations across statistics and cosmological parameters. When combining all the HOS, this increases to a 4.5 times improvement, highlighting the immense potential of HOS for cosmic shear cosmological analyses with Euclid. The data used in this analysis are publicly released with the paper
Euclid preparation. XXXI. Performance assessment of the NISP Red-Grism through spectroscopic simulations for the Wide and Deep surveys
This work focuses on the pilot run of a simulation campaign aimed at
investigating the spectroscopic capabilities of the Euclid Near-Infrared
Spectrometer and Photometer (NISP), in terms of continuum and emission line
detection in the context of galaxy evolutionary studies. To this purpose we
constructed, emulated, and analysed the spectra of 4992 star-forming galaxies
at using the NISP pixel-level simulator. We built the
spectral library starting from public multi-wavelength galaxy catalogues, with
value-added information on spectral energy distribution (SED) fitting results,
and from Bruzual and Charlot (2003) stellar population templates. Rest-frame
optical and near-IR nebular emission lines were included using empirical and
theoretical relations. We inferred the 3.5 NISP red grism spectroscopic
detection limit of the continuum measured in the band for star-forming
galaxies with a median disk half-light radius of \ang{;;0.4} at magnitude ABmag for the Euclid Wide Survey and at ABmag for the Euclid Deep Survey. We found a very good
agreement with the red grism emission line detection limit requirement for the
Wide and Deep surveys. We characterised the effect of the galaxy shape on the
detection capability of the red grism and highlighted the degradation of the
quality of the extracted spectra as the disk size increases. In particular, we
found that the extracted emission line signal to noise ratio (SNR) drops by
45 when the disk size ranges from \ang{;;0.25} to \ang{;;1}. These
trends lead to a correlation between the emission line SNR and the stellar mass
of the galaxy and we demonstrate the effect in a stacking analysis unveiling
emission lines otherwise too faint to detect.Comment: 23 pages, 21 figure
A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)
Meeting abstrac
Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018.
Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field
Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2
The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality
4to. Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad. Memoria académica
Este volumen acoge la memoria académica de la Cuarta edición del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad, CITIS 2017, desarrollado entre el 29 de noviembre y el 1 de diciembre de 2017 y organizado por la Universidad Politécnica Salesiana (UPS) en su sede de Guayaquil.
El Congreso ofreció un espacio para la presentación, difusión e intercambio de importantes investigaciones nacionales e internacionales ante la comunidad universitaria que se dio cita en el encuentro. El uso de herramientas tecnológicas para la gestión de los trabajos de investigación como la plataforma Open Conference Systems y la web de presentación del Congreso http://citis.blog.ups.edu.ec/, hicieron de CITIS 2017 un verdadero referente entre los congresos que se desarrollaron en el país.
La preocupación de nuestra Universidad, de presentar espacios que ayuden a generar nuevos y mejores cambios en la dimensión humana y social de nuestro entorno, hace que se persiga en cada edición del evento la presentación de trabajos con calidad creciente en cuanto a su producción científica.
Quienes estuvimos al frente de la organización, dejamos plasmado en estas memorias académicas el intenso y prolífico trabajo de los días de realización del Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad al alcance de todos y todas
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