2,150 research outputs found
An objective perspective for classic flow classification criteria
Four classic criteria used to the classification of complex flows are
discussed here. These criteria are useful to identify regions of the flow
related to shear, elongation or rigid-body motion. These usual criteria, namely
, , and , use the fluid's
rate-of-rotation tensor, which is known to vary with respect to a reference
frame. The advantages of using objective (invariant with respect to a general
transformation on the reference frame) criteria are discussed in the present
work. In this connection, we construct versions of classic criteria replacing
standard vorticity, a non-objective quantity, by effective vorticity, a rate of
rotation tensor with respect to the angular velocity of the eigenvectors of the
strain rate tensor. The classic criteria and their corresponding objective
versions are applied to classify two complex flows: the transient ABC flow and
the flow through the abrupt 4:1 contraction. It is shown that the objective
versions of the criteria provide richer information on the kinematics of the
flowComment: 11 pages, 4 figures (minor corrections and improvements
Using technology to enhance community health and territorial resources access
Partially supported by FWF Meitner Project M-3338.Improving access to health information and territorial resources can be a way to help strengthen health-related quality of life perception in disadvantaged communities. We argue that, in countries facing diverse economic and social disparities and challenges, technology can be leveraged to improve communitiesâ access to evidence-based, up-to-date, comprehensive, and culturally appropriate supportive territorial resources, thereby improving individualsâ quality of life, especially for those living with one or more chronic diseases. This paper discusses the benefits of introducing and designing a user-friendly, relevant, and effective web-based technology to broaden patientsâ access to healthcare resources and tailored health information, supporting community-based quality of life transformation.Publisher PDFPeer reviewe
Innovation in public-private partnerships (PPPs): the Spanish case of highway concessions
This article identifies the factors that determine innovation in transport PPPs in Spain. Innovation is an important way of achieving efficiency but it is not an intrinsic characteristic of PPP projects. The authors describe the multiple regression model they devised to estimate innovation. The results show that PPP contracts can be designed to maximize innovation in R&D. However, there does not appear to be greater innovation in any other areas. The information provided has important implications for public service organizations considering new contracts with the private sector
Cosmological model-independent constraints on the baryon fraction in the IGM from fast radio bursts and supernovae data
Fast Radio Bursts (FRBs) are millisecond-duration radio transients with an
observed dispersion measure () greater than the expected Milky Way
contribution, which suggests that such events are of extragalactic origin.
Although some models have been proposed to explain the physics of the pulse,
the mechanism behind the FRBs emission is still unknown. From FRBs data with
known host galaxies, the redshift is directly measured and can be combined with
estimates of the to constrain the cosmological parameters, such as the
baryon number density and the Hubble constant. However, the poor knowledge of
the fraction of baryonic mass in the intergalactic medium () and its
degeneracy with the cosmological parameters impose limits on the cosmological
application of FRBs. In this work we present a cosmological model-independent
method to determine the evolution of combining the latest FRBs
observations with localized host galaxy and current supernovae data. We
consider constant and time-dependent parameterizations and show,
through a Bayesian model selection analysis, that a conclusive answer about the
time-evolution of depend strongly on the fluctuations due to the
spatial variation in cosmic electron density (). In particular, our
analysis show that the evidence varies from strong (in favor of a growing
evolution of with redshift) to inconclusive, as larger values of
are considered.Comment: 8 pages, 3 figure
Forecasting constraints on the baryon mass fraction in the IGM from fast radio bursts and type Ia supernovae
Fast Radio Bursts (FRBs) are transient events with a high energy and short
duration in the radio frequency. By identifying the origin of the pulse, it is
possible to measure the redshift of the host galaxy, which can be used to
constrain cosmological and astrophysical parameters and test aspects of
fundamental physics when combined with the observed dispersion measure ().
However, some factors limit the application of FRBs in cosmology: (i) the
current poor modelling of the fluctuations in the due to spatial variation
in the cosmic electrons density; (ii) the fact that the fraction of baryon mass
in the intergalactic medium () is degenerated with some cosmological
parameters; (iii) the limited current knowledge about host galaxy contribution
(). In this work, we investigate the impact of different redshift
distribution models of FRBs to constrain the baryon fraction in the IGM and
host galaxy contribution. We use a cosmological model-independent method
developed in previous work \cite{Lemos2023} to perform the analysis and combine
simulated FRB data from Monte Carlo simulation and supernovae data. Since the
physical mechanism responsible for the burst is still unknown, we assume four
distribution models for the FRBs, namely gamma-ray bursts (GRB), star formation
rate (SFR), uniform and equidistant (ED). Also, we consider samples with , 30, 100 and 500 points and three different values of the fluctuations of
electron density in the , pc/cm. Our analysis
shows that the GRB, SFR and Uniform distribution models present consistent
results within for the free parameters and
and highlights the crucial role of fluctuations in obtaining more precise
measurements.Comment: 9 pages, 2 figure
Accounting for covariate information in the scale component of spatio-temporal mixing models
Spatio-temporal processes in the environmental science are usually assumed to follow a Gaussian process, possibly after some transformation. Gaussian processes might not be appropriate to handle the presence of outlying observations. Our proposal is based on the idea of modelling the process as a scale mixture between a Gaussian and log-Gaussian process. And the novelty is to allow the scale process to vary as a function of covariates. The resultant model has a nonstationary covariance structure in space. Moreover, the resultant kurtosis varies with location, allowing the time series at each location to have different distributions with different tail behaviour. Inference procedure is performed under the Bayesian framework. The analysis of an artificial dataset illustrates how this proposal is able to capture heterogeneity in space caused by dependence on some spatial covariate or by a transformation of the process of interest. Furthermore, an application to maximum temperature data observed in the Spanish Basque country illustrates the effects of altitude in the variability of the process and how our proposed model identifies this dependence through parameters which can be interpreted as regression coefficients in the variance model
Determination of Gluten Peptides Associated with Celiac Disease by Mass Spectrometry
Gluten is a big protein network composed of monomeric fraction (prolamins) and polymeric fraction (glutelins), occurring in many cereal-based products, especially in those containing wheat. Gluten peptides can trigger food allergies and intolerances, including inflammatory reactions as the celiac disease, an autoimmune disorder of the small intestine characterized by mucosal degeneration and villous atrophy. The treatment is the permanent exclusion of gluten from diet. However, gluten analysis is a very difficult task, due to the high complexity of polypeptides and the lack of consensus on the most appropriate analytical method. Proteomics approaches, combining liquid chromatography and mass spectrometry in tandem (LC-MS/MS), have been pointed as the most promising non-immunological techniques for gluten detection. LC-MS analyses associated with bioinformatics and specific-prolamin database can solve methodological limitations since it is based on the accurate molecular mass of peptide biomarkers. One of the major contributions of proteomics has been the identification of epitopes of gluten peptides responsible for wheat-related diseases. Recent works have defined grain-specific gluten peptides and also the lowest concentration at which peptides could be confidently detected. Proteomic application for gluten quantification should support not only regulatory limits in processed foods, but also the safety of consumers about food labeled as gluten-free
Degradation risk assessment: understanding the impacts of climate change on geoheritage
Several factors and processes, both natural and anthropogenic, can threaten the integrity of any geosite, leading to their degradation. For this reason, geoheritage degradation risks should be considered a fundamental step in any geoconservation strategy, all the more when the aim is to tackle the effects of climate change. The present work proposes a quantitative methodology for the degradation risk assessment of geosites by considering the extrinsic factors that can damage the geoheritage. The methodology has been tested on the Maltese Islands, where considerable previous research has been undertaken in order to highlight the international significance of the Maltese landscapes. Three criteria to assess the degradation risk are proposed: natural vulnerability, anthropogenic vulnerability and public use. For each criterion, several parameters have been identified in order to propose a detailed numerical evaluation. The results show that the degradation risk of geosites is mainly related to negligence and lack of knowledge of its inherent geological heritage, and which leads to public misuse and mismanagement of the geosites. The results give an overview of the condition of the geosites and provide information for the design and management of suitable protection measures, especially in the light of future threats related to climate change.Project âTraining new generations on geomorphology, geohazards and geoheritage through Virtual Reality Technologiesâ (GeoVT), funded by the Erasmus+ Programme, KA220 (Agreement number: 2021-1-SE01-KA220-HED-000032142). The research has also benefitted from the FAR2021 Project of the University of Modena and Reggio Emilia (Project responsible: Paola Coratza
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