2,670 research outputs found
2-D constrained Navier-Stokes equation and intermediate asymptotics
We introduce a modified version of the two-dimensional Navier-Stokes
equation, preserving energy and momentum of inertia, which is motivated by the
occurrence of different dissipation time scales and related to the gradient
flow structure of the 2-D Navier-Stokes equation. The hope is to understand
intermediate asymptotics. The analysis we present here is purely formal. A
rigorous study of this equation will be done in a forthcoming paper
Existence and approximation of probability measure solutions to models of collective behaviors
In this paper we consider first order differential models of collective
behaviors of groups of agents based on the mass conservation equation. Models
are formulated taking the spatial distribution of the agents as the main
unknown, expressed in terms of a probability measure evolving in time. We
develop an existence and approximation theory of the solutions to such models
and we show that some recently proposed models of crowd and swarm dynamics fit
our theoretic paradigm.Comment: 31 pages, 1 figur
Comparison between zofenopril and ramipril in combination with acetylsalicylic acid in patients with left ventricular systolic dysfunction after acute myocardial infarction: results of a randomized, double-blind, parallel-group, multicenter, European study (SMILE-4)
BACKGROUND:
Angiotensin-converting enzyme inhibitors (ACEIs) are largely employed for treating patients with left ventricular dysfunction (LVD), but their efficacy may be negatively affected by concomitant administration of acetylsalicylic acid (ASA), with some difference among the different compounds.
HYPOTHESIS:
The interaction between ASA and the two ACEIs zofenopril and ramipril may result in a different impact on survival of cardiac patients, due to differences in the pharmacological properties of the two ACEIs.
METHODS:
This phase IIIb, randomized, double-blind, parallel-group, multicenter, European study compared the safety and efficacy of zofenopril (60 mg/day) and ramipril (10 mg/day) plus ASA (100 mg/day), in 771 patients with LVD (clinical signs of heart failure or a left ventricular ejection fraction <45%) following acute myocardial infarction (AMI). The primary study end point was 1-year combined occurrence of death or hospitalization for cardiovascular causes.
RESULTS:
In the intention-to-treat population, the primary outcome was significantly reduced by zofenopril (n = 365) vs ramipril (n = 351) (odds ratio [OR]: 0.70, and 95% confidence interval [CI]: 0.51-0.96; P = 0.028) as a result of a decrease in cardiovascular hospitalization (OR: 0.64,95% CI: 0.46-0.88; P = 0.006). Mortality rate was not significantly different between the 2 treatments (OR: 1.51, 95% CI: 0.70-3.27; P = 0.293). Blood pressure values did not significantly change during the 1-year follow-up. N-terminal pro-brain natriuretic peptide levels were progressively reduced during the study, with no statistically significant between-treatment differences. Proportion of patients with deterioration of renal function during the study was similar between the 2 groups. Drug safety profile was comparable between treatments.
CONCLUSIONS:
In patients with LVD following AMI, the efficacy of zofenopril associated with ASA was superior to that of ramipril plus ASA, indicating some important clinical implications for the future use of ACEIs in patients with LVD or overt heart failure
New porous medium Poisson-Nernst-Planck equations for strongly oscillating electric potentials
We consider the Poisson-Nernst-Planck system which is well-accepted for
describing dilute electrolytes as well as transport of charged species in
homogeneous environments. Here, we study these equations in porous media whose
electric permittivities show a contrast compared to the electric permittivity
of the electrolyte phase. Our main result is the derivation of convenient
low-dimensional equations, that is, of effective macroscopic porous media
Poisson-Nernst-Planck equations, which reliably describe ionic transport. The
contrast in the electric permittivities between liquid and solid phase and the
heterogeneity of the porous medium induce strongly oscillating electric
potentials (fields). In order to account for this special physical scenario, we
introduce a modified asymptotic multiple-scale expansion which takes advantage
of the nonlinearly coupled structure of the ionic transport equations. This
allows for a systematic upscaling resulting in a new effective porous medium
formulation which shows a new transport term on the macroscale. Solvability of
all arising equations is rigorously verified. This emergence of a new transport
term indicates promising physical insights into the influence of the microscale
material properties on the macroscale. Hence, systematic upscaling strategies
provide a source and a prospective tool to capitalize intrinsic scale effects
for scientific, engineering, and industrial applications
A practical algorithmic approach to mature aggressive B cell lymphoma diagnosis in the double/triple hit era. Selecting cases, matching clinical benefit. A position paper from the Italian Group of Haematopathology (G.I.E.)
An accurate diagnosis of clinically distinct subgroups of aggressive mature B cell lymphomas is crucial for the choice of proper treatment. Presently, precise recognition of these disorders relies on the combination of morphological, immunophenotypical, and cytogenetic/molecular features. The diagnostic workup in such situations implies the application of costly and time-consuming analyses, which are not always required, since an intensified treatment option is reasonably reserved to fit patients. The Italian Group of Haematopathology proposes herein a practical algorithm for the diagnosis of aggressive mature B cell lymphomas based on a stepwise approach, aimed to select cases deserving molecular analysis, in order to optimize time and resources still assuring the optimal management for any patient
Efficacy and safety of pharmacological treatments for patent ductus arteriosus closure: A systematic review and network meta-analysis of clinical trials and observational studies
Efficacy and safety profiles of different pharmacological interventions used to treat patent ductus arteriosus (PDA) are relatively unexplored. Integrating the findings of randomized clinical trials (RCTs) with those from observational studies may provide key evidence on this important issue. We aimed at estimating the relative likelihood of failure to close the PDA, need for surgical closure, and occurrence of adverse events among preterm and full-term infants treated with indomethacin, ibuprofen, or acetaminophen, placebo, or no treatment including both RCTs and observational studies. We searched PubMed, Embase, and the Register of Controlled Trials from inception to October 30, 2018. We first estimated proportions of subjects with failure to close the PDA, subjects in whom surgical closure was performed after pharmacological treatment, death, and subjects with selected adverse events (AEs). These estimates were obtained using frequentist random-effect meta-analysis of arm-specific proportions. We then compared active drugs with each other and with control (either placebo or no treatment) by summarizing results at the end of treatment reported in the papers, regardless of number of administration(s), dose, route and type of administration, and study design and quality. We also summarized primary outcome results separately at first, second and third cycles of treatment. These estimates were obtained using Bayesian random-effects network meta-analysis for mixed comparisons, and frequentist random-effect pairwise meta-analysis for direct comparisons. We included 64 RCTs and 24 observational studies including 14,568 subjects (5339 in RCTs and 9229 in observational studies, 8292 subjects received indomethacin, 4761 ibuprofen, 574 acetaminophen, and 941 control (including placebo or no intervention).The proportion of subjects with failure to close the PDA was 0.24 (95% Confidence Interval, CI: 0.20, 0.29) for indomethacin, 0.18 (0.14, 0.22) for ibuprofen, 0.19 (0.09, 0.30) for acetaminophen, and 0.59 (0.48, 0.69) for control. At end of treatment, compared to control, we found inverse associations between all active drugs and failure to close PDA (for indomethacin Odds Ratio, OR, was 0.17 [95% Credible Interval, CrI: 0.11-0.24], ibuprofen 0.19 [0.12-0.28], and acetaminophen 0.15 [0.09-0.26]), without differences among active drugs. We showed inverse associations between effective drugs and need for surgical closure, as compared to control (for indomethacin OR was 0.28 [0.15-0.50], ibuprofen 0.30 [0.16-0.54], and acetaminophen 0.19 [0.07-0.46]), without differences among drugs. Indomethacin was directly associated with intraventricular hemorrhage (IVH) (1.27; 1.00, 1.62) compared to ibuprofen, and to oliguria as compared to ibuprofen (3.92; 1.69, 9.82) or acetaminophen (10.8; 1.86, 93.1). In conclusion, active pharmacological treatment, with indomethacin, ibuprofen, or acetaminophen, is inversely associated with failure to close the PDA compared to non-treatment. Ibuprofen should be preferred to indomethacin to avoid occurrence of IVH or oliguria, acetaminophen should be preferred to indomethacin to avoid oliguria
Muon Energy Estimate Through Multiple Scattering with the Macro Detector
Muon energy measurement represents an important issue for any experiment
addressing neutrino induced upgoing muon studies. Since the neutrino
oscillation probability depends on the neutrino energy, a measurement of the
muon energy adds an important piece of information concerning the neutrino
system. We show in this paper how the MACRO limited streamer tube system can be
operated in drift mode by using the TDC's included in the QTPs, an electronics
designed for magnetic monopole search. An improvement of the space resolution
is obtained, through an analysis of the multiple scattering of muon tracks as
they pass through our detector. This information can be used further to obtain
an estimate of the energy of muons crossing the detector. Here we present the
results of two dedicated tests, performed at CERN PS-T9 and SPS-X7 beam lines,
to provide a full check of the electronics and to exploit the feasibility of
such a multiple scattering analysis. We show that by using a neural network
approach, we are able to reconstruct the muon energy for 40 GeV. The
test beam data provide an absolute energy calibration, which allows us to apply
this method to MACRO data.Comment: 25 pages, 11 figures, Submitted to Nucl. Instr. & Meth.
Detection potential to point-like neutrino sources with the NEMO-km3 telescope
The NEMO Collaboration is conducting an R&D activity towards the construction
of a Mediterranean km3 neutrino telescope. In this work, we present the results
of Monte Carlo simulation studies on the capability of the proposed NEMO
telescope to detect and identify point-like sources of high energy muon
neutrinos.Comment: To be published on BCN06 proceedings (Barcelona, July 4-7, 2006
Análise de repetições em dados biológicos
The decoding of the genomes has created new challenges on the scientific community linked to the area of computation and information technologies. Daily, new data is added to numerous databases with billions of records, coming from more advanced equipment, helping in decoding the genomes. Determine how important and relevant are these data in order to find value-added information and obviously turn them into knowledge,is the main challenge for the bioinformatics research community. The analysis of genomes and proteomes of several organisms allow us to observe the behaviour at the evolution of species. In this study, our focus goes to a particular aspect of this analysis: the repetition of some codons and their amino acids inside several orthologous genes in eukaryotic organisms. Belonging to different stages of evolution, the main objective focuses on achieving results on the evolution of these repetitions over millions of years. We now know that these repetitions in humans are the source of several neurodegenerative diseases among others. This analysis will verify the conservation or repression, of these repetitions throughout the process of speciation as well at the level of relationship that may exist between these repetitions and those diseases. For this study we have developed an algorithm for A descodificação dos genomas veio criar novos desafios na comunidade cientÃfica ligada à área da computação e da informática. Diariamente são alimentadas inúmeras bases de dados com biliões de registos provenientes de equipamentos cada vez mais evoluÃdos, que auxiliam na descodificação dos genomas. Determinar o quão importante e relevante são esses dados, de forma a retirar valor acrescentado – informação, e obviamente transformá-los em conhecimento, é o grande desafio actual para a comunidade de investigadores de bioinformática. A análise de genomas, bem como dos proteomas dos vários organismos permitem-nos observar o comportamento ao nÃvel da evolução das espécies. Neste estudo focamos a atenção num aspecto particular dessa análise: as repetições de determinados codões e dos respectivos aminoácidos nos vários organismos eucariotas, especificamente em genes ortólogos. Pertencente a várias fases da evolução das espécies, o objectivo principal centra-se na obtenção de resultados quanto à evolução dessas repetições ao longo de milhões de anos. Sabemos hoje que essas repetições no ser humano são a causa de diversas doenças neuro-degenerativas, entre outras, pelo que esta análise permitirá verificar o estado de conservação ou repressão, dessas repetições ao longo do processo de especiação, bem como ao nÃvel do relacionamento que poderá existir entre essas repetições e as doenças nos seres superiormente evoluÃdos. Para este estudo foi desenvolvido um algoritmo de detecção de padrões de repetição, que possibilita uma análise detalhada da localização de uma determinada sequência, bem como das sequências que melhor se ajustam ao padrão de repetição inicial.Centro de Estudos em Educação, Tecnologias e Saúd
Passing to the Limit in a Wasserstein Gradient Flow: From Diffusion to Reaction
We study a singular-limit problem arising in the modelling of chemical
reactions. At finite {\epsilon} > 0, the system is described by a Fokker-Planck
convection-diffusion equation with a double-well convection potential. This
potential is scaled by 1/{\epsilon}, and in the limit {\epsilon} -> 0, the
solution concentrates onto the two wells, resulting into a limiting system that
is a pair of ordinary differential equations for the density at the two wells.
This convergence has been proved in Peletier, Savar\'e, and Veneroni, SIAM
Journal on Mathematical Analysis, 42(4):1805-1825, 2010, using the linear
structure of the equation. In this paper we re-prove the result by using solely
the Wasserstein gradient-flow structure of the system. In particular we make no
use of the linearity, nor of the fact that it is a second-order system. The
first key step in this approach is a reformulation of the equation as the
minimization of an action functional that captures the property of being a
curve of maximal slope in an integrated form. The second important step is a
rescaling of space. Using only the Wasserstein gradient-flow structure, we
prove that the sequence of rescaled solutions is pre-compact in an appropriate
topology. We then prove a Gamma-convergence result for the functional in this
topology, and we identify the limiting functional and the differential equation
that it represents. A consequence of these results is that solutions of the
{\epsilon}-problem converge to a solution of the limiting problem.Comment: Added two sections, corrected minor typos, updated reference
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